Hooniverse Asks: How Can We Fix the Check Engine Light?

Check engine light. Car dashboard in closeup
You dashboard instruments can tell you a lot about your car’s systems, from how fast the engine is turning to whether you’ve been driving for miles with that left-hand turn signal on. One indicator however is as inscrutable as it is important, and that’s the CEL or Check Engine Light.
A CEL can be the sign of anything from a poorly tightened gas cap (thanks Volkswagen) to your engine’s imminent doom so it’s pretty unhelpful that the automotive industry has imbued such weight on so minimalist an indicator. Oh sure, you can plug in an OBDII reader, hell even places like Auto Zone will do that for you for free, and learn what code has triggered the light, but even that’s kind of a half-assed solution.
No, I think we need to reevaluate the whole CEL paradigm. In fact, I say let’s get rid of the CEL in its entirety and replace it with either an indicator light or a natural language readout that tells you exactly what’s going on. That can’t be that hard to do. What do you think, should we be demanding better engine diagnostic tools on our cars? Or, are you happy not knowing what that little light on the dash portends?
Image: CourtHouseAutomotive

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  1. Maymar Avatar

    I have a cheap OBDII reader – that does fine for me. I suppose it would be nice to have the option for onboard displays (as so many new cars have) to be able to show the codes as well, but the portion of the population that can or would use that is negligible.

  2. Justin Hughes Avatar
    Justin Hughes

    Most people don’t care about cars, so they (and manufacturers) are perfectly happy taking it to a dealer or independent shop when the light turns on. But I’d like to see an “advanced mode” available to those of us who do care, which would display the code and its meaning without having to plug in a scanner. It would also save shops the trouble of plugging their scanner in just to get a code. Most cars these days have at least a small screen that could display that data.

    1. engineerd Avatar

      To unlock this mode, you have to use the joystick/controller and enter Up-Up-Down-Down-Left-Right-Left-Right-B-A

      1. jeepjeff Avatar

        You joke, but my Jeep actually does this. If the CEL is on, I can cycle the key on-off-on-off-on and the digital odo will flash the codes. Or: why I do not have an OBDII reader.

        1. Alff Avatar

          It’s a Chrysler thing. My pickup and minivan work the same way. Cheat codes in this instance are silly and diminish “owner experience”.

          1. jeepjeff Avatar

            Really? I am a less is more type, in this case: I don’t like button clutter. It is an advanced feature that most would never use and those that do only need it rarely (yeah, yeah, make your FCA jokes here, but my CEL stays off most of the time). So having to do the hokey pokey to get the codes looks like a good design choice to me*.
            * professional unix sysad: so a lost cause in UX debates…

  3. 0A5599 Avatar

    Pro tip: if you ignore it long enough, eventually the bulb will burn out.

    1. Alff Avatar

      It would be great to be able to selectively clear codes even if the issue persists. I’ve had one on for years, I’m not undertaking the nonessential repair.

      1. dukeisduke Avatar

        Here in Texas you’d have to, since it won’t pass the annual inspection if it’s throwing codes.

        1. Alff Avatar

          Even the government is bigger in Texas.

    2. jeepjeff Avatar

      I hear electrical tape can get a similar result for the impatient.

      1. smalleyxb122 Avatar

      2. 0A5599 Avatar

        When my friend worked at a stealership, they would use a very small drill bit and go straight through the plastic lens to break the bulb.

    3. Tiberiuswise Avatar

      That could take a while if it is an LED.

    4. cap'n fast Avatar
      cap’n fast

      sadly, it’s an LED rated for 1,000,000 hours continuous duty

  4. onrails Avatar

    Between the display in the center of the car or with the gages in most new cars today, it wouldn’t be that hard. Make it accessible with the vehicle in park and ignition on only and you would get past any (hopefully) safety issues. Information in the hands of someone that can do a google search or online chat with a service rep to determine if it’s ok to drive or ‘for the love of all things oily, please fix it now!’ would hopefully at least give the shadetree mechanic of the 21st century a fighting chance, right?

  5. P161911 Avatar

    Have the code display on the dash. Even my 2011 Silverado WT that doesn’t even have power locks, has a display that can show a line or two of text. Maybe have three different levels: Level 1-you aren’t going to pass emissions and might be losing 10% or less gas mileage and power. Level 2-something might break soon, you are losing 10-25% gas mileage and power. Level 3-PULL OVER AND CALL A TOW TRUCK!!!

  6. Alff Avatar

    Allow the code to display on the odometer at the push of a button. None of this start-stop-start-stop-left signal-touch your nose nonsense.

    1. Tanshanomi Avatar

      I would go even further, and actually have a plain-English explanation scroll across the screen: “Fuel tank level sensor circuit malfunction”

      1. Alff Avatar

        What is this “screen” you speak of?

        1. Tanshanomi Avatar

          The little LCD or LED one the numbers appear on. I haven’t seen a mechanical odometer on a new car in years.

          1. jeepjeff Avatar

            Even Jeep Wranglers have had those for the last 20 years.

          2. Alff Avatar

            If you wanted to do that with the odo, the message would have to crawl. Not sure how feasible that is.

          3. Vairship Avatar

            Alternatively, it could simply display the cost of the required repair. That would help focus people’s attention for things like “low oil pressure” 😉

          4. salguod Avatar

            My daughter’s 1998 Escort has a mechanical odometer, I think. The only one in my daily driver fleet.

  7. dukeisduke Avatar

    It’s idiotic that the code isn’t displayed – it’s because the manufacturer is hoping you’ll simply take it to their dealer. Our Sienna is currently getting an intermittent P0717 (Input/Turbine Speed Sensor Circuit No Signal). Once it comes on and won’t go off, I’ll look into it. The van has two speed sensor or top of the transmission (“No.1” and “No. 2”), and given the wording of the code, it’s probably No.1 that’s flaking out. My wife also notices that shifting feels a little different when the light is on.

  8. JayP Avatar

    My 2001 Ford CEL would flash a code for me to google. Saves some grief.

  9. Rust-MyEnemy Avatar

    Some models of B5 Audi A4, including mine, feature a Driver Information System screen in the centre of the instrument cluster. Not only is any warning bleep accompanied by an appropriately instructive symbol, but the symbol is animated too!
    Only snag is when your DIS screen packs in. And it will. Over time they just kind of fade into illegibility, and when that happens you get the scary warning beep but absolutely no clue what it relates to. Your only real option is to stop and check all the lights and levels by the roadside, on the basis that the car thinks that SOMETHING is wrong with SOMETHING.

    1. Alff Avatar

      So eventually the system reduces itself to the equivalent of a check engine light. Seems like a reasonable failure mode.

      1. Rust-MyEnemy Avatar

        Except it isn’t there, and the failure might have nothing to do with the engine at all.

  10. Fred Talmadge Avatar
    Fred Talmadge

    I think most of us have the same idea. Car guys can get code readers. They even have consumer friendly devices. Everyone else ignores it at their own risk or takes it in for service. Cars with screens can display more info as well.

  11. engineerd Avatar

    BMW had CC-ID codes that tell you if there is trouble with any of the myriad of systems on board. Unfortunately, you still have to plug in an OBD-II reader to get DTCs. This seems silly.

    1. nanoop Avatar

      Isn’t OBD2 mandatory? they are forced to have the old connector with the prescribed functions to obey the law, plus a diagnostic connection for all the higher functions.

    1. Rust-MyEnemy Avatar

      JDM Toyota Soarer, Amirite?

    2. Vairship Avatar

      If it’s displaying THAT many warning lights, it’s clearly time to trade it in…

  12. Citric Avatar

    I propose a two tier approach. Level one, stuff anyone can fix it just tells you. Like a loose gas cap you get a ding and it says loose gas cap. For something where you could do some damage it first tells the driver to find someone who knows what they’re doing and that person can prove their competency with a tiny trivia test about the cars affected systems like an old Leisure Suit Larry game as a way to just discourage those whose ambition is far outstripped by their skill.

  13. Fred Talmadge Avatar
    Fred Talmadge

    How about we adapt race car technology. The engineers can monitor our cars and call us with potential problems and solutions. I think the original McLaren F1 allowed you to call the factory and they could connect to your car and do a diagnostic.

  14. Lokki Avatar

    Hardly a new idea to display indicators that show the driver a systems fault. My TR 6 had that back in 1978. Of course it wasn’t digital in those days; the British method was to use sparks and puffs of smoke.

    1. Rust-MyEnemy Avatar

      That’s fine until you run out of harness smoke.

      1. Rover 1 Avatar
        Rover 1

        There are stocks available. You just need to find a Lucas supplier.

  15. I_Borgward Avatar

    A retread, but it seems apropos.
    (tip of hat to Tanshanomi)

  16. Scoutdude Avatar

    The Cadillac Digital Fuel Injection would display codes and actual data on its HVAC or DIC screen depending on the year and model. You would initiate it by holding down two buttons at the same time. Once it ran codes you could cycle through some PIDs thinks like system voltage, coolant temp, torque converter lock up status, rpm, mph in total I think there were 10 or 12 on most cars. Now over course the codes were still just a code and they were much more limited than we have today. So you would get O2 sensor and not O2 sensor always rich, always lean, no response, ect that you have today.

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