Light came on the other day, so I threw the code reader on it to see what was up.
P2177 System Too Lean Off Idle (Bank 1)
P2187 System Too Lean at Idle (Bank 1)
P2096 Post Catalyst Fuel Trim System Too Lean (Bank 1)
P2097 Post Catalyst Fuel Trim System Too Rich (Bank 1)
P2195 O2 Sensor Signal Biased/Stuck Lean
Only other symptom is a hit to mileage (5-10%). Idles fine, doesn't seem to hesitate in normal driving, but I haven't jumped all over it, didn't seem like a good idea to thrash it.
Not an expert at interpreting these things, but that last one seems to indicate a faulty sensor, and then the car going rich to compensate. However, if it's the first sensor failing and then the everything being adjusted lean, why would the post-cat one have an error indicating lean as well?
I did a fairly thorough search for a vacuum leak. If there is one, it's doing a good job of hiding from me and my unlit torch.
The main sensor isn't exactly cheap, and I'd prefer not to just throw parts at this. Potential other causes and/or idea for further diagnosing?
