[paulj]

The check engine light is coming on as I use gas, and if the weather turns colder or wetter. It goes off after a fill, and when things are dryer.

Making sure the gas cap is tight (and clean) does not make any difference.

Any suggestions as to what might be the problem.

Due to the intermittent nature I'm not in a rush to get it too the shop.

 

[Box4Rox]

Did you OBD2 it ?

I've been tracking a similar thing for almost a year now - it's throwing "mis-fire" codes. Been swapping coil packs around to see if it is following a specific coil . . . very intermittent and the car runs fine.

Seems to get worse with humidity and temp changes so I am suspecting a cracked insulator/case somewhere. :-(

155-ish K miles.

 

[paulj]

finally took it in for maintenance. Turned out to be the heater in the secondary O2 sensor. Dealer repair was a bit expensive; fortunately extended warranty covered most of it.