Why the ‘Check Engine’ light must be banned

"Check engine" lights suck! Jason Torchinsky of Jalopnik asks you to sign a whitehouse.gov petition to "require automakers to replace the nearly useless Check Engine Light with a display that actually explains what's wrong."

The continued use of a generic, uninformative "check engine" light in cars keeps car owners in the dark about the condition of their vehicle, and ensures they stay dependent and subordinate to car dealers and mechanics. The frustrating thing is it doesn't have to be that way.

Let's look at exactly what the "check engine" light does in a car, and how it works. To understand it, first we need to understand what On Board Diagnostics (OBD) are — I know for many Jalops this is review, but bear with me.

Every car sold today has an on-board computer system that monitors many, many sensors and conditions in a car's drivetrain, and reports back when there is an error. This has its roots, of all places, in the 1969 Volkswagen Type III, one of the first cars with electronic fuel injection. The "electronic" part of that meant that there was a crude computer brain that managed the system, and could scan for error conditions. Other manufacturers soon had their own systems, and by 1996 an actual, standardized system, called OBD-II, was developed and mandated by law for inclusion in all cars sold in the USA.

OBD-II is actually a terrific system. A global standard for helping to diagnose car issues, with standard connectors and error codes? What's not to like?

What's not to like is that when something goes wrong, all the average motorist sees is that little drawing of an engine bisected by a lightning bolt. And all that tells them is basically nothing. The "check engine" light is the MIL (Malfunction Indicator Light) of the OBD-II system, and illuminates whenever a fault is detected. To see exactly what sort of fault takes a "special scanner" that plugs into the OBD-II connector. These scanners are almost always owned by mechanics or dealers. Independent people can buy scanners as well, or cables to connect laptops, smart phones, etc., but people who will do that are not the ones who need to worry about the check engine lights.

Why The ‘Check Engine’ Light Must Be Banned

• [Richard Dagenais]

  Most motorists don’t check their oil level or know how to change a spare tire and you want to put ODB-II codes in the dash? Such a non-problem.

  • [Victoria Dow]

    Oh what.. you think I’m too stupid to understand a real problem message???? At least I’ll know if the dealership/repair shop is on the up and up.

    • [Barrett Blackwood]

      Get them to print the report from the scanner.

      • [foobar]

        Then I still have to pay a probably unnecessary fee to get the read out.

        • [mccrum]

          No, seriously, it’s totally free if you go to an AutoZone or similar parts store.  You don’t have to buy anything in any manner.

        • [jandrese]

          You can get them for free, but often time the code is something like “Dealer Code #7″, which means you have to go to the dealer to get the actual diagnostic, and the dealer does charge you to decode that. 

        • [mccrum]

          I’m not trying to beat a dead horse here, but I’m pretty sure if you put in Nissan OBD-II code you’ll get something like this, which not only has Nissan codes but other manufacturers as well:
          http://nissanhelp.com/diy/obd_codes/nissan_engine_codes_chart_2.htm

    • [salvodan]

      No offence, but most Qualified Mechanics don’t understand what a real problem message means.
      V6 Alloytec engines get stretched timing chains if the vehicle isn’t maintained or the engine is abused.
      I don’t know how many Cam Position Sensors I’ve sold, even after telling the mechanic that it won’t solve the problem. Their Aftermarket Scan Tool says CPS so they blindly do what it says.

    • [Richard Dagenais]

      No I’m saying that if you are smart you know how to get the codes and interpret them. Its not like having a spare tire; over 90% of users do not desire or require this. The engine light serves its purpose just fine.

      What would be cool though would be if the newfangled digital binnacles on cars would have an expert mode built in so you could turn on more info if you care to have it, like odb-ii codes for smart people like Victoria Dow. :-)

  • [xunker]

    In fairness, I hope most motorist aren’t that bad.. I hope.

    These new guideline suggestions aren’t for those people anyway.  ”Those people”, those who are militantly and purpose ignorant of their vehicle, would ignore everything in their car even if there was a a giant LCD on their steering wheel that said, in flashing and flaming comic sans:

    “YOU CAR IS OUT OF OIL AND WILL BLOW UP IN IN 500 YARDS IF YOU DO NOT STOP IMMEDIATELY!”

    …”Those people” would shoot for 600 yards.

    • [Art]

      …1000 yards as long as you stay under 55 mph :)!

    • [blueelm]

      I’m one of those people. I just ran out of gas today. Granted though I’ve kept this car running for 15 years and over 150k miles. I hate having a car. I hate cars. I hate driving. I wish I didn’t live somewhere that required it because it is pure stress and the only thing that I dread more than driving is buying a car (which will happen soon I’m sure).

      Also: my check engine light has been on for many years.  Passes everything else but the light is on.  It goes off some times, but typically stays on. Converter I think they say.  It would be more expensive to fix it than my car is worth though. Did I mention I hate cars? 

      I’d like this though, it might actually be more helpful for some one like me, if it could distinguish between sensors well. In my case I replaced two O2 sensors to no avail years ago and then just decided I’d wasted enough money chasing ephemeral problems in an old car.

      I have checked on my own though with a computer, and the response is equally vague. It is either the converter, one or both sensors. That’s not much help. If you get responses like that, prepare to spend a few hundred digging around just looking for where to spend the next few hundred I guess.

      Yeah… really really really hate cars. :(

• [skormos]

  If the “Problem” light was good enough for Dr. Prof. Jonas Venture, then it should be good enough for the rest of us!

• [hypersomniac]

  Nightmares of mechanics telling me my car passed smog, but it’s illegal for them to pass it because the check engine light was on.

  “Oh yeah, well what’s wrong with it?”

  “That’ll cost you another 200 dollars to run a diagnostics scan.”

  (In my mind) “F*cking crooks.”

  • [penguinchris]

     You can get an OBD reading device for well under $200, so if this is something that regularly happens to you it would probably be worth your while :)

    I mean, even if it happened just that once, you could have bought a device yourself to check. Most cars also have a way to reset the check engine light – so if there isn’t an actual problem (many modern cars will set off the light if the gas cap isn’t screwed on all the way, for example) you can try resetting the light. If it goes back on, then of course you’d want to run a scan.

    • [Steve Nordquist]

      Why would I want to operate a car, made after 1969, again? If only there were some kind of universal serial bus, an audio output device expected to chime when the car is being boarded, or because of ODB-II insurance logging dongles the service state of the car were shared semi-monthly. I never want to run a scan; the thing often comes from an ISO-90000 facility, condition-hardness of semiconductor parts is not an unsolved problem, was the ECU off starting a Poi-Poi troupe or something? Do Detroit et al spend lobbyist time fighting HDMI ports or Bluetooth that let on about senile automotive pleuresy (empty and massage inlet hose -here-) for the chime-impaired? 

      Lessigwise, law or a court ruling looks necessary to clear the old laws, requiring a horse lantern to illuminate when any beast’s jowls fall.

  • [D Wyatt]

    ANYONE CAN BUY A READER ONLINE FOR USUALLY LESS THAN $75.
    I would say about 50% of the time its something RIDICULOUS AS HELL.  For instance, I was constantly getting a “check engine light” that ended up being my gas cap wasnt screwed down tight enough….

    Also most autozones will allow you to use there loaner one for free, they just wont let you turn the light off and delete the code.

    • [bob ross]

      yeah they will, every time I’ve borrowed one from autozone the device had the ability to clear all codes (which shuts of the light). Although if it’s a serious issue the light will turn back on.

    • [iamzuul .]

      Agree with the ridiculous as hell aspect. I owned a truck for 7 years and 80k miles (made it to nearly 200k before it finally died for good) with a constantly on check engine light, because the previous owner had welded on a replacement part for a different version of truck, rather than use the correct one. It was virtually no different, but just different enough to set off the light. It was pretty much impossible to fix (would cost thousands) and no one was willing to turn the light off permanently. So I just ignored it. Never made a difference or cause any harm.

• [tylerkaraszewski]

  The people who won’t buy an ODB-II scanner are the same people that will still take their car to the dealer to get it fixed when the “faulty oxygen sensor” light comes on instead of the generic “check engine” light. The diagnosis of these problems, simply because you *can* buy the scanner, is not the big barrier keeping people from fixing their own vehicles. It’s the lack of knowledge on how to (for example) replace an oxygen sensor.

  A cheap ODB-II scanner can be found on amazon for $30. I’d you can’t get one of these, then you can’t get any of the other tools to repair your car, either.

  • [merreborn]

    A $30 ODB-II scanner will only read a subset of standard codes.  There are a bunch of manufacturer-specific codes that require more expensive equipment to read.

    Or so I’ve been told.

    • [MrJM]

      My cheap scanner gives me all the codes, but some mfg-specific codes aren’t in the accompanying book.  But I’ve been able to find every code all on them interwebs.

  • [Gyrofrog]

    Mechanic I usually visit charges $80 to get and read a code.  After I got my own code reader, the next time I went in,  I said “well my code reader already told me it’s this.” He said, “yeah but I still have to read the code myself.”  Think I’ll be going elsewhere (assuming they’re not all like this).

    • [Nagurski]

      Find another mechanic. An honest one won’t charge you for the 30 seconds it takes to read the code.

  • [Zacqary Adam Green]

    Self-repair isn’t the point. Right now, if the problem is the oxygen sensor, there’s no reason that the dealer or mechanic can’t say, “oh, and also you need a new head gasket and radiator and first-born child.” This type of display would empower everyday people to call dishonest mechanics on their bullshit.

    Yes, even the types of people who mightn’t be able to operate an ODB-II scanner, who aren’t stupid people who have it coming to them. As geeks who know how to use an Internet comment form, it may not occur to us that technology is actually really, really difficult to use and understand.

• [mccrum]

  When mine goes off I go to the same place I buy wipers and they hook it up, print out the data and diagnose it well enough to determine if there needs to be additional repairs.

  I agree with Richard Dagenais, this is not a problem.  I’d rather have one light that indicates “check the computer” with a real person who I can talk to about the issue instead of a code on the dash telling me to check the manual which then only confuses the matter further.  Seriously, have you ever really read that thing?  Changing a tire takes 20 pages and doesn’t actually tell you to put the lugnuts in the hubcap.

• [Emarcroft]

  Both times I can think of my car having a major problem, the check engine light didn’t go on – major smog fail and empty radiator due to a big crack – and plenty of other times when I took it in for the check engine light being on it was for something as lame as “oh, a spark plug misfired once, it couldn’t be reproduced, go on your way.” Not sure having the more descriptive scanner would have helped me with the former, but definitely for the latter I would have said, ah, ok, I’ll keep an eye on that, but no reason to take it in if a spark plug misfired once or twice and isn’t misfiring now.

• [The Rykin Effect]

  I don’t see the big issue. You can either buy a scanner or go to an Auto-parts store and they will lend you their scanner for free.

• [Stonewalker]

  Y’all are headed towards being the proud recipient of the prestigious ‘nanny of the month’ award.  While I agree that the check engine light is crude and nearly useless (and co-incidentally, CA does not allow a car to pass smog if the light is on… costing us more money), banning it is not the right approach.

  Getting CA to repeal that stupid law and regulate the smog process in some other way would be better.  Scanners are cheap nowadays anyways.

• [travtastic]

  Standardize the scanner connectors to USB.

  • [yatesc]

    Better yet, USB and a Bluetooth antenna.

    • [failquail]

      Bluetooth has potential hacking implications with it.
      Not entirely convinced having a wireless connection associated with engine electronics is that great an idea from a security standpoint…

      Probably a bit paranoid, but i think a wired connection would be best all round. Plus USB (full mini or micro sized) is about as standardised and cheap as you can get for a generic computer connection nowadays.

• [Barrett Blackwood]

  OBD-II error codes only diagnose sensors that are out of range or faulty. OBD-II cannot directly diagnose mechanical faults. It takes a mechanic to diagnose and understand whats actually causing the sensor fault. A readout on the dash would not be of any use to the average motorist.

  However, some check engine lights are programmed to automatically come on at intervals (every 6 months, etc. ) to try and force the owner to bring it into the dealership regularaly. Each manufacturer has a different secret method of resetting these lights. (sometimes holding a button, a hidden button, pumping the brakes in a sequence, or using a OBD-II reader to reset the code.)

  • [Matt Jones]

    The car I’ve been looking  at (Fiat Panda) is like that, the service indicator pops up when it thinks it’s due a service, and can only be reset by a main dealer. There isn’t a way for a DIY mechanic to do it, even though the servicing is perfectly easy to do.

• [Adam Cahan]

  Of all the potential federal laws that could make the U.S. a better place, this one rates pretty low on the priority list. Nonetheless I learned some cool stuff about car brains and CELs.

• [xunker]

  We are forgetting that we do already have more descriptive displays in our cars, we have the MIL light _and_ the “Oil pressure Light”.  Some cars (though not many now) even have an “Alternator” warning light that misleadingly looks like a battery.

  Using these handy warning lamps we can deduce thusly:

  * ALTERNATOR LIGHT: you are about to be stranded, hope you brought walking shoes.
  * CHECK ENGINE LIGHT: your car may be fucked, life’s a lottery, be lucky.
  * OIL PRESSURE LIGHT: your car is most definitely fucked, ha ha.

  • [Stonewalker]

    Oil Pressure Light – you mean the “idiot light” right?  :)  The one that means “no oil, engine going to seize up in seconds!!”

    • [xunker]

      Agreed:

      Check Engine Light: Are you an idiot?
      Oil Pressure Light: Yep, you are!

    • [PNWchemist]

      it means shut you engine off NOW coast to a stop and check to make sure you still have oil… then figure out why it’s throwing the light… on my 95 OBD 1 vw jetta the both of the oil pressure switches like to go bad, cracked or broken crank case breather hoses will cause the light to go too, hard cornering, the wrong viscosity oil, or an incorrect oil filter (thanks jiffy lube)

      Check engine light is usually a bad sensor, sometimes the second O2 sensor or something else, but not the end of the world most of the time.

      I agree about the alternator thing, grab a wrench pull that thing off and take a cab to the autoparts store. 

    • [Max]

      With you of course being the idiot in question. Oil pressure and oil level are not always related. Adding oil just because the pressure light has gone off is very likely to FUBAR your engine, especially if you have a turbo.It could be simply a kinked pipe. faulty pump etc. or, yes our oil could have escaped, but it might all still be there.This sort of highlights the issue of why the “check engine light” is actually a good thing. Tell some idiot “low oil pressure” and he reads “low and oil” pressure having multiple syllables gets forgotten, oil gets added and boom big problem.Try mention crankcase breathers and before you know it you’ve got some arse lying under the car blowing through a tube.If you know what you’re doing the OBD readers are as cheap as a decent set of spanners and just as useful If you don’t know  what you’re doing, having a built in OBD reader is as useful as having a built in left handed bifurcated flange torque wrench calibrated in mega dynes per atto parsec. TAKE IT TO THE GARAGE.What is shocking and should be illegal is dealers charging extortionate rates to read the codes. There should be a mandated charge of 25 units of currency for the garage’s newest oik to pop his oily hands on your upholstery, plug in and say “you had a misfire on cylinder 2 about 3 weeks ago”  or “it’s got a constant over heating oil warning” or whatever.

• [Ben Chatterton]

  This discussion calls to mind Lawrence Lessig’s “Code”, in that the Jalopnik piece is arguing for law (“East Coast Code” as LL calls it, as in Washington, DC) when a hack (buy the scanner or get a code scan for free at an auto parts store) would do just as well. Seriously, the scanners really are cheap. That being said, the existing system does prey on the uninformed. The cure for that is free information, as a law will only solve the problem inasmuch as people are willing to abandon their ignorance.

• [Steve Schroeder]

  Interestingly, some cars come with the ability to check the OBD-II codes already.  My ’05 Magnum had a nice system for it, and for my ’06 Charger, there’s the “Key Dance.”  Simply cycling the ignition from accessory to on (but not starting the car) three times pops up any stored codes into the dash display.  With code in hand, you can search online and typically find a forum post detailing information about the code, what it means, and how to fix it.  

  And, as others have mentioned, handheld scanners can be purchased inexpensively, and several auto parts stores will scan the codes for you for free.

  • [ahecht]

    Agreed, one of the few things I really like about my Chrysler is that I can do the “key dance” and get an error code whenever I get a check engine light (the number of times I’ve had to do this recently, however, is one of the many things I really DON’T like about my Chrysler).

• [Bull Moose]

  AutoZone will print out the malfunction codes for free. At least in my state.

• [bo1n6bo1n6]

  With all the advancements in cars and computers one would think the car could inform a person with the problem/severity of the problem/nearest place to fix the problem/how to fix the problem, am I right or am I right?

• [skeptacally]

  in my experience, 9 times out of 10 it means that the wiring/switch to the “check engine” light is faulty.

  • [Bad Juju]

    Let me guess, VW, or other fine European machine?

  • [sofa king]

    no.  9 times out of 10 it is that the ‘fuel filler cap’ is loose or not sufficiently tightened.  (and some cars won’t reset the light when the condition is fixed… have to go to the dealer to get them to clear the code!!!!)

• [Sam Ley]

  Have to agree with @Stonewalker:disqus  – surprised at the “the sheep-le are too stoopid to understand what is going on with their car, keep them in the dark” responses.

  Not everyone will fix their car, nor should they, but it encourages healthy competition and enhanced consumer awareness to give them information. If the car says, “Check engine”, people either take it to the dealer and just pay them whatever they ask for, or take it to Autozone, convince them to clear it, and ignore the problem. In neither case are they getting the best service possible.

  I’m thinking something like a bug report – car says, “Fault detected with Bank 1 Oxygen Sensor. Datalog of last 10 minutes of throttle position, timing and AFR has been generated and stored on your SD card.” You could email this to a dealer or mechanic and get some information on what needs to be repaired before bringing it in. Why double the diagnostic time by requiring that the mechanic 100% rediagnose the problem?

  Likewise, many faults can be caused by things that ANYONE can fix on their own, such as a bad gas cap. Why pay a dealer $120 an hour to diagnose and repair something that anyone who is capable of filling their own tank could fix? What if your car just said, “My gas cap has failed and is increasing harmful emissions. Replace with part number #AB2023 available at any Subaru dealer or auto parts store.”

  The datalogging features inherent in ODBII are quite good – I can take amazing logs of what is going on with my Subaru WRX, down to knock detection, AFR, boost pressure, etc., which can be used by mechanics to remotely tune or diagnose problems. Really incredible. Unfortunately you need an expensive and somewhat complex device to take those logs.

  And ultimately, providing MORE and CLEARER information to consumers always results in an improvement in efficiency, cost and satisfaction. Think about MPG indicators on modern vehicles, which have been shown to do wonders for people’s driving habits. Give them the info in an clear and concise manner, and it will help.

  • [Jer_00]

    “but it encourages healthy competition and enhanced consumer awareness to give them information.”

    THIS.

    Jeebus people – capitalism doesn’t work right when information is hidden from one side of the transaction.  It’s like people are arguing “oh no – if EVERYONE could read the OBD-II codes on their machine then how would I impress my friends with my 1337 knowledge of computer diagnostics?”

    If a message shows up on the LCD, some people will Google it to find out what it means.  If that helps them to know in advance whether their repair is going to be in the $50 range or the $500 range before they go to the mechanic, that helps all of us (as it improves competition and weeds out crappy mechanics who can’t do their jobs without taking advantage of uninformed customers).  Who cares about how smart you are – freeing up this kind of information can only make life BETTER for everyone who isn’t a shoddy, lazy mechanic out to deceive people.

  • [Max]

    The car isn’t that clever. If it tells you that you should buy a new petrol cap, you buy one and the problem doesn’t go away, you sue. If you go to a garage, it says “new petrol cap” then someone with experience might ahve a quick look and say “your filler pipe is cracked, not only are you failing emission tests but you are leaking petrol every time you fill up”

    Either the computer has to be able to monitor EVERY aspect of the car to a ridiculous level of monitoring or there has to be a skilled person involved. 

    Remember : Cars are big complicated weapons. Every time you get behind the wheel you’re driving a ton of metal that could easily kill many people at speeds up to a hundred odd miles an hour (or up to 55 in the USA).

    Do you want a computer guessing what’s wrong with it.

    Hell : Windows can only guess 99% of the time when things go wrong “An unspecified error has occured” NOT helpful when that’s your car brakes and yours and someone else’s life is on the line.

    • [C W]

      “Either the computer has to be able to monitor EVERY aspect of the car to a ridiculous level of monitoring or there has to be a skilled person involved.”

      What a laughably stupid dichotomy.

• [foobar]

  He’s followed up with a petition on whitehouse.gov

  I’m never going to fix my car. I can’t even be bothered to change my own oil, but I would plug a USB cable into my laptop if I had the option.

• [Bad Juju]

  If your CEL’s gone on & it’s not your gas cap, something reasonably catastrophic has happened & you probably shouldn’t be allowed under the hood anyway, because you’ve been ignoring obvious signs. There’s a reason they call it an idiot light.

• [Jaeryn Spedden]

  As a mechanic, I’d just like to say- LOL. For FREE you can go to AutoZone, have them read the code and they will print you out the code, what it means and the most common reasons why the code would be thrown. O’Reilly is also starting to do it. (O’Reilly HAS to do it per corporate pressure, but a lot of employees have an “I’m not a mechanic” mentality and may refuse you.) A cheap OBD-II reader can be picked up online, at Harbor Freight Tools or many auto parts stores for $30 and up. Yes, they don’t come with what the codes mean all the time- but that’s what the internet is for. They DO make ones that plug into a USB, so you can hook it up to a computer. They also make a hook up and software for around $100 that connects with your iPod Touch or iPhone.

  90% of the codes that the CEL throws are for emissions related issues. The most common being an O2 sensor code or the EVAC leak small code indicating the gas cap is bad or you didn’t put it back on. If your engine is truly le fucked, it won’t usually throw a code. If you grenade the transmission or throw the timing chain on a newer car, it will show up, but that’s about it.

  The one that should be banned- the “Service Engine Soon” light. It is easily shut off on most cars by the normal person, but you need to be taught how to do it or look it up online. Your typical place to get an oil change should also know. The issue I have with it- it puts people into panic mode. All it means is that the car hit the “required” service interval. And on some cars (new Nissans come to mind), the light comes on for the oil change every 3k miles, but the owner’s manual recommends the service be done at 6k.

  • [C W]

    “As a mechanic, I’d just like to say- LOL. For FREE you can go to AutoZone, have them read the code and they will print you out the code, what it means and the most common reasons why the code would be thrown.”

    As a mechanic, you’re not the vast majority of consumers, who should be able to do this themselves without having to go to Autozone or buy the ODB for THIS common of an error.

    • [mccrum]

      Speaking as a non-car-enginey person (I wash it, but I’ve never changed my own oil) going to AutoZone to find out that I did have an O2 sensor issue was that much of a trial for me.

• [EarthtoGeoff]

  Why are so many people willing to go out and buy an additional device for an automobile you already paid so much for?

  I mean, it seems obvious from this thread that it’s not only possible to diagnose it yourself, but also inexpensive. But jeez, I see no reason to so aggressively stick up for the car companies who could be designing a better product.

  If my car radio can read MP3s, then the diagnostics should be able to do better than tell me something is wrong in the engine somewhere.
   

• [Listener43]

  Ah, the check engine light – a warning that can mean anything, but usually doesn’t.

• [jdollak]

  The only time I’ve ever had to have a mechanic check the diagnostic computer, it was around 2000, and it cost about $200 to have it hooked up.  The argument was made that this was a silly thing to charge for – they don’t charge all of us for the cost of the wrenches they use.
  I can see that things have changed, but it’s still an easy way for mechanics to make easy money off of customers without the background knowledge they should have access to.

• [Max]

  Bottom line : Do you trust Windows to tell you what is wrong with your PC when it crashes?
  If you do, then you’ll be happy with the updated informative information from OBD on your dashboard.

  If you can’t trust Windows to get your PC right, then you are the sort of person who realises computers are not omniscient, despite what was promised in the 60s.

  When you don’t trust Windows, do you let someone who has no understanding of PCs diagnose the fault or do you ask someone (maybe yourself) who has a clue.

  So, if you wouldn’t let someone with no clue diagnose your PC, why do you think people with no clues should be diagnosing their car?

  • [C W]

    I trust embedded systems to know better than certain software ecosystems, yes.

• [Graysmith]

  My car will sporadically show the Check Engine light. It’ll show for weeks at a time, disappear for a month, come back and so on and there’s nothing wrong with the car. One time the light even appeared on the drive home from the mechanic who’d just done standard upkeep and maintenance on it (i.e. the least likely time the Check Engine light should turn on).

  • [Jaeryn Spedden]

    Usually a wiring fault. Best bet is to try to get it read while it’s on. Mine does the same thing. Will show up for a week or 2, then go off for months at a time. Sometimes its on a day to day basis. The issue is the wiring on my 2nd O2 sensor. I don’t care enough to fix it.

• [israel]

  Personally I think the current system is pretty good, but I’m kind of a car guy.  I feel like the $30 scanner and 5 minutes of googles is a reasonable barrier to keep total dumdums from messing up their cars.  It keeps dealerships in the money from folks who wouldn’t fix the thing themselves anyway, and lets those who are inclined do so with minimal (imo) hassle. 

  I have one of those expensive and somewhat complicated devices Sam Ley mentioned above for my Subaru, but had to go buy a cheapy code reader to diagnose a CEL (as they’re called) on my wife’s 2001 Accord. 

  My older car , a 93 RX-7, is ODB I.  To read any error codes on it, you have to jump a couple terminals on a relay under the hood, then watch the light and record its flashes (long – short and number of each) and then you’ll need a service manual to look up the codes.  ODB II seems pretty easy by comparison, yes?

  Also, if you know nothing about cars but want to know, just ask a car guy.  Most of us don’t mind being helpful.  :)

• [etherist]

  I bought a 30-dollar bluetooth OBD-II dongle off of ebay, and thanks to a $5 android app called “Torque”, I can stream car data to my cell phone, check and reset codes, log coolant temps, etc.

  At least I can when it’s working.  I think the last “update” to Torque borked it, hopefully it’s only temporary.

• [daneyul]

  I hate fucking sensorship.

  The information is there, in my car.  Obfuscating it is bullshit.  So is telling people to  “just order a reader” .  Especially considering most people aren’t going to do it until an error appears and then it will take days to arrive. 

  And saying I should drive to some 3rd party site just to have them read it for “free”?? My time and trouble are not free–and the information is already there.  Give me what’s mine.

  • [ChicagoD]

    “My time and trouble are not free.”

    I bet you wish that was true, but once the check engine light goes on you will discover that it is not.

• [petsounds]

  Here’s a solution. Have the TSA take over automobile safety and change “Error code” to “Terror code”. Every time you go through a mandatory highway inspection point, the TSA will helpfully check your car for any Terror Codes. The Government and The People, Working Together Always.

• [Derek]

  I always thought the “check engine” light was far too non descriptive. Reading through these comments – I don’t see why it would not be reasonable to just add a small LCD readout underneath it stating what the error codes are, if there are multiple codes, a button to cycle through the codes?  like with windows cryptic Errors: “0043F”.

  It means nothing to people who don’t care about it, and they’ll be able to say to their mechanic “It’s doing this”, which allows for quicker diagnosis – and the DIY types can google the results and decide whether they want to deal with it themselves or take it in for service.

  Using the “check engine” light as a “needs service” light is disingenuous, and if there’s nothing wrong with it, it should say that it needs service, I think newer, higher end holdens do this.

  There’s no good reason to hide information behind a service port.

• [Julien Couvreur]

  That’s funny because the stupid MIL light is a federal mandate in the first place.

  See the linked section from “Code of Federal Regulations, Title 40, Protection of Environment, Pt. Pt. 85-86 (Sec. 86.599-99), Revised as of July 1, 2010″ which is available on Google Books:

  http://books.google.com/books?id=q8_vHlaJHVwC&pg=PA200&dq=Malfunction+indicator+light+OBD&hl=en&ei=h4j-TNSEFoiDOpaCvc4M&sa=X&oi=book_result&ct=result&resnum=1&ved=0CC0Q6AEwAA#v=onepage&q=Malfunction%20indicator%20light%20OBD&f=false

  That said, I do wonder why more cars don’t offer a more detailed display (in addition to the mandated MIL), which seems desirable for their customers and many cars come with built-in LCD displays nowadays. You’d have to ask a car company about that.

  Personally, I don’t buy the simplistic argument of “evil profit-seeking car manufacturers” you raise above. If consumers really want this (and are willing to pay the supposedly small cost that comes with it), car manufacturers would use such a cheap feature as differentiation to win over customers. High-end cars do have similar error displays for low-pressure tires, so competitive pressure should presumably also work for other diagnostic displays.

  Rather I suspect the diagnostic is not as simple or useful as you think. The question is whether ODBII codes are specific enough for most common problems, or if they only indicate some broad condition which needs an experienced mechanic to troubleshoot (ie. there could me multiple causes). 

• [Palomino]

  Per  Steve Schroeder above, the writer of this article doesn’t know much about cars, and shouldn’t have authored it. Most new models, 90′s and up, will yeild a code by simply cycling the ignition switch. It’s sad that, for years, billions of dollars have been spent by consumers who pay their licensed mechanic to “hook your car up to our very expensive monitor” only to drive it round back and get the code by cycling the ignition switch.  

  If this author is really interested in saving the American public billions of dollars, stop the auto industry from designing parts with special fastners that require a single special tools that the public can’t purchase. (Thanks to 3d printers, when they become common this won’t be the case anymore.)

• [Jaeryn Spedden]

  The cars that have the ability to tell you by cycling the ignition key are cars that have a digital dash. Not every car has those. You want something really fun- the 80s Mustang had a display that told you when anything was low and what light was burned out. I believe some BMWs also have this.

  For those of you saying this is a good thing- how old is your car? I own a 95, a 00, an 02 and an 03- none of them have a digital dash, so the car won’t show me a code. So my option is a $30 code reader or a $20,000+ new car. Which would you choose? The normal person would much rather buy a code reader or buy a display that you can add to an older car (they exist) than buy a new one. This “law” would only affect new cars, and just give people something else to freak them out. Just like when they made the Tire Pressure Monitoring System mandatory. That was amazing. Suddenly tons of people were running to tire shops freaking out cause the light was on.

  And the big thing that baffles me with some of the people commenting- If you’re going to fix it yourself- then you’re going to have to buy parts. How is going to the part store  out of your way? And if you work on your own car, you should have a code reader anyway. If you’re going to take it in to a shop- How is going to a shop to have it read going out of your way? You’re already there. Drop it off and have them fix it once they figure it out.

  If the display is going to tell you what’s wrong- will you be able to shut off the light yourself? In states that require emissions testing, this would allow anyone to shut off their check engine light in the parking lot before being tested and pass even if something is wrong. (Not saying that you can’t do this with a code reader, but this would open the option to everyone.) And just because you know what it is- doesn’t mean that you can/will do anything about it.

• [bcsizemo]

  Actually most everyone here is missing the bigger picture of what the check engine light should tell you.  How fucked you immediately are.  Obviously if the check engine light and oil pressure light come on you are probably headed for an expensive repair bill, but if you O2 sensor is off that’s not a really big deal.  Yes it probably needs to be fixed, but you are safe to drive your car until someone can look at it.  For the most part you can lump ODBII codes into categories of fix now, or fix later.  And there are a whole lot more fix later codes, than fix now ones.

  I’m a car guy, I have a scanner, so it’s no big deal for me to pull the codes…but it’d be nice to know if my wife is riding down the road and the check engine light comes on she doesn’t have to freak out because of a loose gas cap.  Why can’t we just have a yellow light for a check soon problem, and a red light for a get to a garage now problem?  Seems easy enough to me.

  (and yes I’d like to see cars that can tell you the codes, but it more important to me to know how bad that code is without having to consult something to look it up.)

  • [Donald Petersen]

    Everybody oughta go read the Wikipedia article on the Malfunction Indicator Lamp.  It’s instructive.
    My 82-year-old mother called me the other day in a small panic because the Check Engine light came on while they were out & about, and my Dad wasn’t overly concerned about it.  I told her not to worry, he knew what he was doing, and like he’d told her, if the trouble was serious, the light would be flashing.  If, on the other hand, the car seemed to be running okay and the oil pressure and temperature gauges looked nominal, it meant the car was unlikely to crap out anytime soon.

    OBD-II was made mandatory on all cars sold in the United States starting with the 1996 model year.  One of the ways that it was a step up from OBD-I was the fact that all the cars used the same standardized data connector, and it was required to be within 2 feet of the driver’s seat, rather than under the hood or stashed someplace inconvenient.  Back in 1996, automakers didn’t really have affordable technology for cars to tell you, in plain language, what was wrong with them, and OBD-II was a reasonable compromise between affordability and accessible information.  Also, most of the DTCs (diagnostic trouble codes) were standardized, since most internal combustion gasoline engines operate pretty much the same.  Whether you drive a 1999 Jaguar or a 2003 Chevy, if the code reader displays P0171, then the oxygen sensor in bank #1 has detected a lean condition.  Is it because of a dirty Mass Airflow Sensor?  Possibly a vacuum leak?  How about a clogged fuel filter?  Could be any of those… but it narrows down the possibilities.  If you really want to know what your car’s trying to tell you, then yes, certainly go buy a code reader.  Some of them will allow you to reset the MIL and turn off the lamp.  If not, one could always disconnect the battery (making sure to remember any codes needed to unlock your stereo or alarm thereafter).  The car will need to be driven a bit (maybe a couple days) to re-adjust idle and mixture and other computer settings from the factory default, and if there is a genuine non-intermittent MIL-triggering problem, the light will come back on pretty soon anyway.  But if it’s a rare triggering (like the gas cap thing), then disconnecting the battery will reset it.  Then again, for minor, occasional troubles like those, the light will eventually extinguish itself after a few days of trouble-free driving anyway.

    Maybe it is, indeed, time for automakers to replace the OBD-II standard (or at least enhance it) with plain-language diagnostics viewable on the increasingly ubiquitous touch screen.  Indeed, I’m pretty confident automakers would be moving in this direction even now, if they still wanted drivers to know what’s wrong with their cars.  Maybe this is, indeed, something that needs to be legislated into place, as OBD was.

• [prion]

  If you don’t have the gumption to read your own codes, you simply are incapable of the diagnostics that follow obtaining those codes.  A certain aptitude is required for most pinpoint testing, even with google or shop manual help. I won’t feel bad for the individual who is too (lazy?) to understand more about their own vehicle while blaming the CEL for themselves not understanding more about their own vehicle.

  • [prion]

    The concern should be that car makers are moving away from vehicles that owners can service themselves, full stop.  The problem is that this has been happening for a long time, and there is no easy rallying point for an online petition that combats this.

• [Incipient Madness]

  Oil pressure light coming on while idling means your car is screwed if you don’t get attention fast.

  Check engine light often means nothing.
  http://www.youtube.com/watch?v=KMhp2ShPVQw

• [Lara M]

  Oh, way to push a button.
  I’m a girl. *gasp* I’m also an engineer’s daughter. *Yay!* And when my Astra (Opel / Vauxhall / Holden) started flashing its “check engine” light at me? I asked Dad and Googled like mad. Turns out you *can* read the check engine codes by a trick with the pedals and counting flashes. A silly angle sensor needed replacing, apparently one that has a tendency to go in Astras.So it was due for a major service and I turned it in. By myself. I explained what was happening, what the codes were, how it was functioning.”Oh, we’ll run our computer over it -”"But I told you what the codes were.”"Oh, you can’t possible know what the error codes are -”"No, really, let me show you the trick, or you can Youtube it. And I’ve already checked the error codes, I’m not sure if they link up with the European codes exactly (being a Holden) but …”I got some very sympathetic nods from the big strong men who clearly didn’t believe me, and when they proved to themselves it was the angle sensor (very kindly waiving the ~$100 fee to do so) they then told me it would cost a terrifying amount to replace. I returned that evening with several other estimates on the cost of the part, but they looked at me blankly and told me if I didn’t want them to fix it that’s fine. Somewhere in checking the sensor, they clearly broke it because long explanation short, the car was barely functional when I picked it up.

  I ranted at Dad. I surfed car forums and explained to him the most common causes of issues with the sensor, the prices for the part, and what I thought of the mechanics. Big protective Dad brings my car down to the lot – and they replace the part at cost price.

  Just. Codes being easily accessible? Would leave one less thing for car mechanics to sneer at me (or feel intimidated when I already know :D). (And when I bought a new car, it was from a salesman who sold the car to *me*, not my supervising Dad. Given that he convinced both of us that space-saving tyres are not as awful as they look, he gets points.)

• [ChickieD]

  I would like to have the full code, maybe I don’t need a law to get it, but here’s a good example of why:

  I’ve had two rounds of brake repairs lately and after the last round of repairs my brake light came on once again. I took the car to the mechanic and left it all day, because I feared it was another major brake repair. I needed to get the issue addressed immediately, too, because I planned to take the car out of town in a couple of days and I didn’t want to risk having brake problems while I was traveling.

  My employer has an issue when I have to get a ride with a co-worker and come in late, so I’d rather not leave my car all day unless it’s necessary. As it turned out, the brake fluid was low. There was no need for me to leave the car – I could have popped by my mechanic on the way home and had him top me off in a couple of minutes. And I didn’t need to feel like this was such an urgent, potentially expensive issue, but could have known immediately that it was a minor issue.

• [phil koltko]

  While I agree that the average (and even above-average) motorist isn’t going to be helped much by a code such as “Lean Mixture, Bank One” (a code that my Kia had thrown a while back), one thing struck me while reading the comments:

  Many, many people are saying “OBD readers are cheap”.

  If that’s the case (and I agree that it is), then HAVE THE CARMAKERS JUST INCLUDE THE DAMN THINGS! Either as a plug-in gadget that resides in the same compartment as the jack, or by integrating it into the existing electronic displays as the post’s author suggests. 

  While making the information more easily available will probably not help the average Joe/Jane, keeping it hidden/cryptic helps nobody but the dealers/mechanics. 

  But failing that, the combination of AutoZone and Google will get you as good or better information than “Joe’s Auto Service $75 Check Engine Light Special”.