My 2000 540i sport 6 speed has been throwing codes, doesn't have the power that it should and is not running as smoothly as it should. A while back it was setting P0170 and P1340 codes, so after a bit of forum searching I decided to replace the pre-cat O2 sensors and the cam position sensors. I replaced the O2 sensors first and the difference was nothing short of amazing! Smooth, powerful, ran like new.
Unfortunately this lasted only for about 50 miles and it slowly started degrading again. By this time the cam sensors came and I replaced those, but there was no improvement except that I have not seen the P1340 code since, but still get P0170 every couple of weeks or so. A couple thousand miles later and now I am getting P0150 and P0155. These both refer to the O2 sensors.
Could my new O2 sensor(s) be bad? Any ideas? I had a taste of true 540i performance for 50 miles and I want it back! Help!