one bank running rich
 

I had a CEL pop up this morning, P0175, bank 2 (left hand) too rich. Since bank 1 isn't affected I am ruling out things like ECT, fuel pressure, or MAF. But that leaves less desirable items like a fuel injector, coil, or O2 sensor.

500 miles ago I changed the plugs and the engine has been running great since. It actually stopped pinging (but if it's running rich that explains why that happened). The plugs may be completely unrelated, I only mention that because a misfire would cause a rich condition.

I don't feel anything like a misfire, except a few weeks ago I noticed it started having an odd idle blip. After fully up to operating temp, if I stop at a long light, I'll get an occasional idle rpm drop (like if you turn the wheel and the power steering lugs the engine). Normally it sits at 610 rpm, after about 1.5 mins it'll start doing a little drop to 580 rpm, then back up to 610. It might do this a couple of times, 10-15 seconds apart. Doesn't do this when warming up or at a short light.

Anyone have any thoughts on this? I am inclined to clear this code and see if it comes back. I remember years ago I had an issue where I would get a bank 1 lean code, it would stay for just one drive cycle, then go away on its own and didn't come back.

Hi m,

There's no harm in clearing the code to see if it recurs. It may just be spurious.

Cheers,

Don

Instead of clearing it
1. read and note the freeze frame data
2. check fuel trims

Something is almost certainly wrong.

Clear the code if you like but I'd fix the fault if one is shown above.

I did write down the freeze frame info before clearing it. I was surprised to see bank 2 at -20% (caused the CEL) and bank 1 at -18%! So they are both running rich. However, it appeared to be during a deceleration (25 mph, 10% throttle). I will watch the fuel trims while driving and see how they look. So far the LTFT for both banks is between 0 and -10%.

I will dig into this further.

Might be a bad/dirty MAF.

Don't know your car data... see below