Yes another P0125 thread. I recently replaced my oil pump gasket because it was leaking like crazy and after i got the car all back together and fixed the leak i took it for a casual cruise. After driving for 6 miles the car got the cel for P0125. Now the car is running rich almost all the time on the uego, at idle im at 10.7 and while trying to maintain speed on the highway by barely pushing the throttle its pegged at 10.0
If i go to get into boost it starts fluctuating like it normally should until wot on a pull where its around 11.5

I did read all the old threads regarding this code and i am tempted to order a new front upstream O2 sensor and possibly a coolant temp sensor to see if it will resolve the problem.

 

Bump for help...

 

Possible causes:


- Low engine coolant level
- Leaking or stuck open thermostat
- Faulty Engine Coolant Temperature (ECT) sensor
- Engine Coolant Temperature (ECT) sensor harness is open or shorted
- Engine Coolant Temperature (ECT) sensor electrical circuit poor connection


Start at the top. Replacing the thermostat worked for me.

 

If a harness problem, since the sensor resistance becomes less with heat, a false low temperature reading would be an open.

 

Front O2 sensor was the problem...

All fixed...