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.
Become a TTAC insider. Get the latest news, features, TTAC takes, and everything else that gets to the truth about cars first by subscribing to our newsletter.