OK.. I'm trying to help my boss fix his 94 turbo wagon. He's had a baaaad surging problem for a few years now. Been throwing money at it for a while now too. He's spent close to $2000 on this REALLY bad mechanic who's done everything (supposedly) to fix our problem.. I took the car for the weekend and decided to do my own diagnosis.. First off, the throttle body was never cleaned.. EVER... same with the IAC.. I cleaned both extremely well. Checked out all the stored codes and reset everything. The car runs GREAT now.. But the engine light still comes on as soon as it's started and I am still getting codes 221 and 231. Both of which state a lean mixture.. the fact that this comes up the very second this car is started is kinda odd.. Does the Oxygen sensor work that quickly? is there any kind of learn mode or timeframe after a code reset? Do these codes mean the oxygen sensor is bad? I've done all the other prerequisite checks. The AMM disconnected stalles the car out.. disconnecting a vaccum hose brings the RPM's up some.. I can't find a vaccum leak anywhere..

Anything else i should look for? Thanks for any help. hte car is decent except for the having to replace the door latches and a few other things.. Hate to havee the poor guy keep throwing money at a mechanic who shouldn't be fixing cars in the first place.

 

You can check the O2 sensor with a volt meter.Put the positive lead on the single green wire and the other terminal on ground and the needle or digital volts should sweep up and down.