The check engine light is the single stupidest warning light in existence


I solved the problem by spending less than eighty bucks to get a device that talks to my phone to tell me what the light is actually saying and gives me the ability to reset the thing.


Really the light should be re-labeled as “Emission Fail” because (at least here in WA state) when that light is on, all it really means is that you’re going to fail your next emissions check.


There’s a reason why they call them “Idiot Lights.”

OTOH, my first car was a hand-me-down '76 Cadillac Seville with random electrical problems after it was flooded by a burst water main in heavy traffic.

While I was driving it a yellow “stop engine” warning light came on and I ignored it as always. A short while later a red “STOP ENGINE NOW!” light lit up and I paid attention. Turns out there was a radiator leak and the car was all but on fire.


Uh, not in California, where it will prevent you from passing your emissions inspection, and thus you won’t be able to register the vehicle.


In my experience, as long as you take your car in for maintenance at scheduled intervals the check engine light never becomes an issue. If the vehicle has a reputation for throwing errors for no reason, then why the hell did they buy the car to begin with? Try buying a machine that’s actually reliable next time.

Either way, ignoring the light is the stupidest possible solution. Cars aren’t biological, whatever’s causing the light to illuminate won’t heal on its own.


My issue with it is the complete lack of gradation in meaning.

Does “check engine” mean “see a mechanic at the next convenient time?”

Or does it mean “turn off the ignition now to avoid throwing a rod?”


Actually, it sometimes does. That’s what makes this particular light the most annoying.

Next down on my list would be “low tire pressure” lights that won’t turn off until you’ve been driving for 15 - 20 minutes after bringing the tires back up to proper pressure…


It can also come on if you’ve got a hole in your oilpan. At which point continuing to drive will result in your having to buy an entire new engine and possibly even having an accident due to a piston flying up through your hood or something equally dramatic. If you stop, though, you could save a couple grand…

And that’s the whole problem. As the article says:

The problem is that – by putting such a wide array of faults under the banner of one simple orange light – we’ve conditioned ourselves to ignore it. Your see the check engine light go on, but the car feels fine, and it sounds fine, and it acts fine, so your move on with your life, without regard for whether you have a loose gas cap, or a faulty oxygen sensor, or an adult hedgehog living inside your muffler.

Mind you, I won’t ignore it, but that’s only because I’m my own mechanic. I immediately pull over and connect to the on-board diagnostic computer to determine what the actual fault is. But that’s only possible because I keep an ODBC reader handy… @SteampunkBanana has the same solution.


Best line: ‘And if you have a Land Rover, a light comes on that says “YOU’RE AN IDIOT.”’


They’re great, right? Totally inexpensive and well worth the peace of mind. Mine actually works like a car computer and keeps track of things while I’m driving allowing me to review logs afterwards and determine if there’s something going on before it becomes an issue.


Not owning an OBD scan tool for your car is like not owning a monitor for your computer. How else are you supposed to know what’s going on inside?


Most auto parts stores will read from the OBD II port for free, and give you a list of possible causes.
With, of course, the caveat that they have no responsibility for being correct.
A recent idiot light of mine meant anything from a gas tank fill sender failure to the whole computer failing. I know the fill sender is wonky: on cold days it will flip between correct fullness and empty periodically. I can live with that so long as most of the time it’s showing the right value.


Sounds like what my son does - he’s got an android app that continuously monitors a bluetooth ELM327 ODBC link from his phone, giving him real-time feedback on how his driving is influencing his gas mileage. Total cost about $20.

I don’t have a cell phone, but I use an old Nook running CyanogenMod and Torque in my plug-in Prius, works fine and again cost less than $20 because I got the Nook for free.


FWIW Auto Zone (or one of the similar places) will read the codes for you for free if you’re too cheap (whistles and looks around innocently) to buy an OBD reader.


Check engine lights remind me of this:


Any recommendations? My wife loves data tracking stuff, so I am looking for a “set it and forget it” solution.

In a world according to me, cars would come right from the factory with a display in the middle console with lots and lots of gauges for all that is happening inside the car and especially the engine. Exactly like aircraft have.

In real world it can be made as an aftermarket mod with a cheap tablet. And will give you something to amuse yourself with in traffic jams or at red lights.


With the wide availability of digital displays it seems like manufacturers could create more specific warnings. Once the “check engine” light alerted me to a problem that the repair guy told me would need to be fixed eventually, but wasn’t an immediate threat.

At the very least there needs to be a warning that says, “You might wanna get that looked at when you have time.”


They won’t even test the car in CA if the light is on, which is probably best.