'03 R50 with 92k. Check engine light came on so I ran the scanner and P2097 came back. Replaced the post cat O2 sensor and the code kept getting thrown each time I reset it. Bentley "Diagnosis Without Guesswork" book also mentioned that the fuel trim adaptations needed to be reset after this repair and that a special scanner could do this.

I searched for other ways to reset the fuel trim and discovered that there was no way other than the special dealer scanner to do this. I also ran into many that had said that this code means the pre cat O2 sensor needed to be replaced. I switched the new one into the pre cat position and put the old post cat sensor back in place. Still getting the P2097 code. Any ideas? I don't really want to pull that pre cat sensor out again but I could. I also don't want to buy another sensor.

Will the fuel trim adaptations eventually reset themselves? Fuel mileage for the tank that was run with the light on before I did anything was really bad- 23 mpg instead of 29-30.

Val