It seems like getting behind the dash to unplug the light would be more work than actually fixing most problems that trigger a CEL.
not if the cause of a CEL is a circuit fault instead of a failed part. tracing circuit faults in a typical wiring harness bundle can be a right pain in the ass.
This is a prime example of why when somebody says just read the code and replace the part those of us that do this stuff for living shake our heads.
It ain’t that easy folks. Analyzing O2 sensor signals front and rear as well as running parameters to determine if it is a cat and which one is a skill.
Your car has 3 cats so you have either 3 or 4 O2 sensors to read as well as the other running parameters.
What kind of car is it and what codes have set?
My 97 BMW has had the “Check Engine” light on since 2001. Runs better every day, I swear.
Just don’t have Sheldon as a passenger…
Harness faults are fairly easy to diagnosis. You check the wire in question for continuity, short to ground, short to power finds about 95%+ of all harness faults.
Harness faults come in three general flavors.
- At a connector. Bent pin, backed out pin, corrosion. Easy to fix.
- Failed harness due being physically damaged. If it was routed wrong at the factory and a sharp bracket or something similar cut the harness. Finding it can be hard. Repair can be easy, but in severe cases the harness must be replaced.
- Rodents. Usually easy to fix. They eat a couple of wires and quit. Again repair or replace.
The car I referred to above was notorious for “rub-throughs” (wires abraded their insulation away and shorted together) and invisible breaks (copper wire breaks but the insulation stays intact) inside the main engine harness. Picking apart that bundle and finding the suspect wires was not fun, especially with so little room to work.
And there must be something unique about the high temp insulation used on O2 sensors. Rodents love to chew on those things.
It must have been an older model, as modern cars will not run if the CHECK ENGINE bulb in the dashboard is removed. of course you can cover the lens in the dash with black electrical tape etc.
Does anyone else find this scary?
“I can’t do that, Dave”…
Every day brings news of another hack - meanwhile, we rush to “the internet of things” - I can’t wait for the first hack of a cloud-controlled train (why bother stopping? or activating the grade-crossing wig-wags?)
Not true at all – that is just flat wrong. I don’t know where you get these ideas, but the misinformation is not helping.
the only way unplugging the check engine light will cause trouble is if you live in an area which mandates emissions inspections. the first thing they’re supposed to do is verify that the check engine light is lit when the cluster does the brief “tell-tale” mode* after you turn the car on. If it isn’t, your car fails.
- “tell-tale” mode is when the gauge cluster turns on all of the warning lights for a few seconds after turning the key to RUN so you can verify none of the bulbs or LEDs are burned out. some cars also have a test mode for the cluster where you can call up the tell-tale on demand.
The light had turned off again when I started up on Saturday – I will still put in the new gas cap and wait and see.
Your car and my car must be talking to one another. My 2009 Elantra has been doing the same thing for maybe 4 to 6 weeks now.
What I think I noticed though, is that it seems to toggle on when the outside temperature changes significantly. I may be imagining it, or it may be coincidental, but it seems like the light will go off after a few days of driving and stay off until the next major temperature delta whereby it turns on again for three or four days.
Lather, rinse, repeat.
I imagine the weather in NH has been swinging a lot this winter, as in Ottawa.
Engines don’t shut down when there’s a indication of low oil pressure, which is generally understood (even by non car guys) to be an engine-destroying condition. So why would the engine deliberately shut down for a flashing MIL?
Yes, a flashing MIL is rare, because that sort of problem (severe, persistent misfire that sends large quantities of unburned mixture to the cat, overheating it) is rare. It’s not necessary to see or hear of it happening in order to understand what a flashing MIL means; all you need to do is read the owner’s manual, which any person in the internet who boasts “I’m a car guy” ought to know.
FWIW, if someone’s car deliberately shut itself down in the middle of Death Valley because they got a flashing MIL, there would be a massive lawsuit over the resulting deaths.
You really should stop participating in this thread; the Dope’s reputation for straightness is suffering because you keep spreading misinformation.
Modern cars will run just fine, no matter what you do to the MIL bulb, but they’ll throw a code, and of course the MIL won’t light up at key-on, which is pretty much a dead giveaway.
Despite the many miles separating them, my Corolla has always felt that it could tell when your Elantra was sick, injured or just upset. I guess this seals it.