a couple of weeks ago my "service engine soon" light came on (solid, not blinking). i took it to the dealership and the code was P0301 (misfire cylinder 1). they reset, checked a couple of things and said it might have been a glitch. see if it comes back. a few days later it did, but this time the code it threw was P0305 (misfire cylinder 5). so they said the O2 sensor for cylinder 1/3/5 was the culprit and replaced it. the very next day the light comes back on again! i called and am taking the car back in next week. here's the strange part: this morning the light is still on, but when i take the car out this afternoon it's off! huh??
it happened one other time while i was waiting for the O2 sensor to come in (it went out for a day or 2 then came back again).
any insight as to why this might be happening? once it throws a code i thought it would stay illuminated until the dealer reset it, no?

 

What do you have for mods if any?

 

no engine mods at all.

 

Strange... The only thing i have heard causing this issue is a non tight connection with an after market intake, and or the MAF is dirty. I had the same issue with my stillen G3's making the MAF dirty because the tubes came really dirty. THe only other thing i can think of is that those settings in our car are really tight stock and on cold start up in cold weather can cause this issue temporarily

 

funny you mention the cold weather thing...the light first came on when the temperatures began to drop significantly (down into the teens and twenties). yesterday it was 44 degrees here and that was when the light went out. it's cold as hell again today though. i'll have to take it out later and see what happens.

 

I would be willing to bet that's what it is. I the light goes out its most likely nothing serious. But get it checked out anyway, just don't be shocked if they don't find anything

 

I know this is old but did you ever figure out your issue?

Dead battery jumped the car and then got a cylinder 5 misfire. Haven't cleared the codes but could it be dirty MAF/TB? What fixed it for you?