I have a 2010 Jetta with the 2.5L 5-cylinder that recently threw on the check engine light for 2 days, then the light shut off. It began once I started the car on a coldish (~20F) morning after it had been sitting curbside for several days with the passenger side wheels sitting on about 6 inches of snow so the car was listing to the side. The car fired up immediately but ran extremely rough for about 10 seconds (the engine throbbed sharply about 2-3 times per second, which could be felt through the steering wheel & seat, accompanied by a muted clunk) before I turned it off. During this time the CEL flashed on and off and then stayed on. I popped the hood, peered stupidly at the plastic engine cover, and restarted the car about a minute later and it ran normally, but the CEL stayed on. I drove it for two days (~50 miles) with the CEL on, but on the third day (today) the CEL did not turn on. The car has been running normally for all three days. Any ideas of what might have caused the rough idle/CEL and whether I can pretend it never happened since the car seems to be running normally for the third day in a row and the CEL has turned off on its own?
I wouldn’t mind canceling my dealership appointment later this week and saving some time, but would like the opinion of the folks on this website before I do.
Sounds like you had a plug that wasn’t firing for a moment…then it began working again…this can happen…not serious…it would throw a “misfire code”…Then after a few days of working fine…it cleared.
I need to check and see IF a misfire code CAN clear itself…I think it can…but need to check… Minor codes have the ability to clear…more serious ones MUST be manually cleared
Just take the car to Autozone and have them read stored codes. And don’t drive a car with the CEL on for 3 days. It’s a good way to end up buying your mechanic a boat.
Thanks for the info Blackbird, I hope it is just an isolated fluke.
RemcoW & shadowfax, I went by an Autozone equivalent on lunch today, they said they cannot read a code if the CEL is not currently on, so we might be taking that trip to the dealer anyway. The manual for my car states that if the problem is serious the CEL will flash rather than stay lit. The definition of serious is not elaborated on!
The dealership will probably just charge you a whole bunch of money to shrug at you. I wouldn’t bother unless you have this issue again.
Chances are good, btw, your fuel system had completely drained down while the car sat and the period of poor running was from a lack of fuel. A flashing check engine light is most often a severe misfire - in this case a lean misfire. I’m just guessing, of course. But I would leave it alone until it shows some other sign of an issue.
If it sits for a long time again you could do one of two things. One is “sort of” hope it happens again so you can get the codes read & maybe get to the bottom of it. Or, two, turn the key to the run position and back off about 10 times before cranking the car. (“Run” is where all of your dash lights come on but before it cranks over). This will repressurize & refill the fuel lines.
"There is nothing to read when the CEL is not illuminated…
That’s not quite true depending on how a manufacturer sets things up & what kind of equipment is being used. Some scanners, for instance, will pick up pending and history codes and others won’t. Pending & history codes don’t come with a light. Then there are also all sorts of codes that can be current, but aren’t ones that won’t trigger the dash light. I assume this is because they are not emissions related. But it doesn’t mean they’re not about malfunctions. My GM is like that - dumb like a rock, I say.
This car’s PCM may still have the history codes in it, but not just any code reader will find them.
Many thanks again for the additional information, folks. This car is under warranty, so the dealer will not be charging me to look at it, and said they can read the stored code if the CEL is not lit.
Next time it has sat for awhile I will turn the key to the run position for a few more seconds before cranking.
My appointment is tomorrow and I will post the findings.
Turning it to the run position for a few seconds won’t help. The fuel pump only energizes for a few seconds until you crank it. That’s why you’d have to cycle it on/off/on/off a whole bunch of times. It only pumps up a little each time.
But given the warranty (I didn’t pay attention to how young the car is) you shouldn’t have to mess with it at all. Make them figure it out & set it straight. Don’t let them tell you that anything about this is “normal.” Its not normal is everything is working correctly.
Returned from dealer. Faulty ignition coils on 2 cylinders. They replaced all 5. I’ve read that this was common on nightmare Jettas from the early 2000s, but is supposedly much less frequent on this generation. At 20K miles this is a little worrying, but Consumer Reports and True Delta indicate significantly improved reliability for Jettas since 2005. Hopefully my car is near the mean and not an outlier in the wrong direction…
True a Snap On Diagnostic scan tool will actually pull previous code history…I should’ve caught myself after I wrote that…But I was also thinking in the context of the OP going to Auto Zone or similar…and there they wouldn’t see any codes bec of their simplistic tool…
But Yes you are correct as usual Cigroller…I’m getting awful tired of that…LOL
That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.
But if it is under warranty, why worry. It is dealer issue. Go to the dealer so you will have a documented history of the problem and what you did.