Has anyone swapped bank1 pre cat 02 sensor on there 35i or 35is themselves? Is so was it at all possible to do it from above or is it a definite under the car job ? I had bank 2 one done with my indy garage last year and quite a few pounds as they always get parts direct from the dealers and a sensor was nearly £300 plus about 3 hours labour. I can get a Bosch sensor for around £90.