I had a check engine light (yellow outline) at 3,700 miles. My hand held scanner said "p2096 post cat fuel trim to lean bank 1." Took it to my dealer; they re-flashed the ECU after O2 sensor inspection. The check engine light went away; 400 miles later, boom check engine (yellow outline). Back to the dealer I go; they replaced the sensor under warranty. I have no issues now. Anyone else have O2 problems with their R56?

Please don't just blame the exhaust, I'm just looking to report an issue and gain some knowledge

 

I had my pre-cat O2 sensor replaced under warranty this week at abour 4500 miles. Check engine light came on during the trip home from work one day last week. Drove about 400 miles over the weekend with no big problems other than a seeming loss of power a couple of times. Shut it down for a couple of days and then tried to drive it to work again. Idle quality was so bad after about 30 seconds of running that it almost went dead. Finally gave up and put it back in the garage. MINI of Nashville sent a truck for it. Diagnostics (don't have the code in front of me) led them to a bad pre-cat O2 sensor. I'm going for a day trip tomorrow. We'll see if it stays fixed.

 

Guys - what fuel grade are you using in your cars? I had a VW Golf that had the same issues that kept coming up (O2 sensor)....even though I was using premium...it was during a time when gas prices were very high (this was in Australia) and gas stations were adding ethanol (illegally) to the point where it was messing with the 02 Sensors.

Proving gas quality issues is a hard thing when fighting against a service station...

 

Always 93 Shell...from multiple fuel stations. No issues and now at 5500 for the replacement.