Opinion: The Check-Engine Light is Useless

opinion the check engine light is useless

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]

Join the conversation
2 of 92 comments
  • 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.

  • ToolGuy @Matt, let me throw this at you:Let's say I drive a typical ICE vehicle 15,000 miles/year at a typical 18 mpg (observed). Let's say fuel is $4.50/gallon and electricity cost for my EV will be one-third of my gasoline cost - so replacing the ICE with an EV would save me $2,500 per year. Let's say I keep my vehicles 8 years. That's $20,000 in fuel savings over the life of the vehicle.If the vehicles have equal capabilities and are otherwise comparable, a rational typical consumer should be willing to pay up to a $20,000 premium for the EV over the ICE. (More if they drive more.)TL;DR: Why do they cost more? Because they are worth it (potentially).
  • Inside Looking Out Why EBFlex dominates this EV discussion? Just because he is a Ford expert?
  • Marky S. Very nice article and photos. I am a HUGE Edsel fan. I have always been fascinated with the "Charlie Brown of Cars." Allow me to make a minor correction to add here: the Pacer line was the second-from-bottom rung Edsel, not the entry-level trim. That would be the Edsel Ranger for 1958. It had the widest array of body styles. The Ranger 2-door sedan (with a "B-pillar", not a pillarless hardtop), was priced at $2,484. So, the Ranger and Pacer both used the smaller Ford body. The next two upscale Edsel's were based on the Mercury body, are were: Corsair, and, top-line Citation. Although the 1959 style is my fav. I would love a '58 Edsel Pacer 4-door hardtop sedan!
  • Lou_BC Stupid to kill the 6ft box in the crewcab. That's the most common Canyon/Colorado trim I see. That kills the utility of a small truck. The extended cab was a poor seller so that makes sense. GM should have kept the diesel. It's a decent engine that mates well with the 6 speed. Fuel economy is impressive.
  • Lou_BC High end EV's are selling well. Car companies are taking advantage of that fact. I see quite a few $100k pickups in my travels so why is that ok but $100k EV's are bad? The cynical side of me sees car companies tack on 8k premiums to EV's around the time we see governments up EV credits. Coincidence? No fooking way.