Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I've got an intermittent bank 2 too rich code on my neighbors van. Seems to happen while sitting at idle most of the time. That makes me think of a leaking injector, but then it will suddenly snap out of it. Could be that it stops leaking I suppose. It will throw a p0300 code as well and while it's happening, b2s1 o2 sensor is stuck at 720Ish mV. I pulled the brake booster and woke it back up, forced lean then it was oscillating again and running well. I just had the upper intake off recently to do spark plugs for them and wish I put the injectors on my flow bench while I had it off! Visual inspection showed no wire damage to that o2 sensor. Bank 1 fuel trims look fine and bank two pegs out negative when this happens.
3.6L engine? If you can get it to act up again, it'd be cool to see what the B2S2 is doing at the same time. If it's showing full lean, the upstream is lying. If it agrees, then the rich condition is real.
If you haven't run into it yet, bank two on these engines have cam follower/lifter/cylinder head issues. Not saying that's your issue, but it's common enough that I think it's worth mentioning. Usually shows up as a single cylinder misfire at idle.
Local dealers (around here, anyway) have been pretty good about offering extended warranty coverage. Of all the cars I've sent to the dealer, only one was told to pound sand. :lol:
Good to know. I'll add that I just checked mode 6 and found misfires only on 2,4, and 6. That makes me want to move away from a leaking injector. I haven't been able to get it to act up again but noticed while looking at the two front o2s that bank 2 responds about half as fast when I put it in gear to load it. They both go lean, but bank one starts changing much faster and the same when I put it back in park, both go rich and bank 2 is the slow poke. Not sure if that is an indication of anything since it looks fine otherwise.
If I can get it to do it again I'll check the rear sensor.
Tyler, I just read the tsb for the head issue and it is definitely worth looking into. Sounds like it could be the issue here. Thanks for the heads up.
Not saying that's your issue, but it's common enough that I think it's worth mentioning. Usually shows up as a single cylinder misfire at idle.