Opinion: The Check-Engine Light is Useless

Tim Healey
by Tim Healey

I was running an errand Sunday in a Mercedes S-Class tester when all of a sudden I saw the “check engine” light had popped on.

“Huh, that’s odd,” I thought to myself. Especially since the car was running and driving just fine.

Indeed, the next morning, the light was off.

I checked with the press fleet and I was told the dealer did a remote scan (I didn’t even know this was a thing) and found the car needed a software update. So, no big deal.

But I have to wonder — what’s the point of the check-engine light (CEL) if it doesn’t tell me, the driver, much about what’s wrong. I had no idea if there was an issue with the emissions components or the on-board diagnostics, or if the gas cap hadn’t been tightened by the previous driver (I hadn’t put fuel in the car or otherwise accessed the cap). All I knew is there was either something wrong or the computer thought there was something wrong, yet the car was experiencing no obvious drivability issues.

We need a better system. I am just not sure what.

Certainly, having error messages with specific problems pop up would confuse the general public. Most drivers don’t know a spark plug from a plug wire, and you can’t really expect the average driver to read an error message on the dash and know when to go to the dealer and when not to.

But on the other hand, many drivers do dash to the dealership the second the check engine light pops on, even if they end up finding they simply didn’t tighten the gas cap. Other folks, usually those who are driving older cars that are well beyond warranty, ignore the CEL because either they can’t afford extensive repairs and/or they’ve taken the car in before only to find the issue was minor and not worth spending money on.

The current system is set up so that if your CEL is on, you generally need someone with a scan tool to plug in and find out what the error is (or, I guess, you can get a software update). Sure, scan tools aren’t the exclusive domain of professional techs, but no matter who is wielding it, one is needed to figure out why the light is on.

I’ve never bought into the idea that the CEL is so nonspecific because the OEMs want you to spend money on diagnostic fees instead of fixing issues yourself. That’s because if it’s a customer pay job, the money spent on labor is going to the dealer, not the OEM, and if it’s a warranty job, it’s going to cost the OEM money. Not to mention consumers sometimes choose independent shops.

But I do find it quite annoying that the CEL can pop on, and I, the driver, have no idea why. Not knowing how much I need to worry is something that gives me anxiety.

Yeah, I know, we all hate the guy who points out an obvious problem without a proposed solution. And sorry, I got nothin’. All I know is there has to be a better way.

[Image: virgmos/Shutterstock.com]

Tim Healey
Tim Healey

Tim Healey grew up around the auto-parts business and has always had a love for cars — his parents joke his first word was “‘Vette”. Despite this, he wanted to pursue a career in sports writing but he ended up falling semi-accidentally into the automotive-journalism industry, first at Consumer Guide Automotive and later at Web2Carz.com. He also worked as an industry analyst at Mintel Group and freelanced for About.com, CarFax, Vehix.com, High Gear Media, Torque News, FutureCar.com, Cars.com, among others, and of course Vertical Scope sites such as AutoGuide.com, Off-Road.com, and HybridCars.com. He’s an urbanite and as such, doesn’t need a daily driver, but if he had one, it would be compact, sporty, and have a manual transmission.

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  • Daniel J Daniel J on Oct 02, 2021

    Honestly, most of these cars have a USB input. These cars should have the ability to download diagnostic logs straight to the USB stick.

  • Ithappenedthatway Ithappenedthatway on Oct 04, 2021

    I remember when the CEL was called an “idiot light” Times were simpler then.

  • CanadaCraig You can just imagine how quickly the tires are going to wear out on a 5,800 lbs AWD 2024 Dodge Charger.
  • Luke42 I tried FSD for a month in December 2022 on my Model Y and wasn’t impressed.The building-blocks were amazing but sum of the all of those amazing parts was about as useful as Honda Sensing in terms of reducing the driver’s workload.I have a list of fixes I need to see in Autopilot before I blow another $200 renting FSD. But I will try it for free for a month.I would love it if FSD v12 lived up to the hype and my mind were changed. But I have no reason to believe I might be wrong at this point, based on the reviews I’ve read so far. [shrug]. I’m sure I’ll have more to say about it once I get to test it.
  • FormerFF We bought three new and one used car last year, so we won't be visiting any showrooms this year unless a meteor hits one of them. Sorry to hear that Mini has terminated the manual transmission, a Mini could be a fun car to drive with a stick.It appears that 2025 is going to see a significant decrease in the number of models that can be had with a stick. The used car we bought is a Mk 7 GTI with a six speed manual, and my younger daughter and I are enjoying it quite a lot. We'll be hanging on to it for many years.
  • Oberkanone Where is the value here? Magna is assembling the vehicles. The IP is not novel. Just buy the IP at bankruptcy stage for next to nothing.
  • Jalop1991 what, no Turbo trim?
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