I have a 2008 Cooper S with 95K miles. 2 months after purchase, the P0141 code for the number 2 O2 sensor came up. I replaced the sensor with a cheap $28 aftermarket Chinese one. The light went out for a week and then one day the car ran rough for a minute and stalled backing out of the driveway. Got it running again enough to get it back in the driveway, and it would hunt at idle. A few days later the CEL came back on with 6 codes: P0141 again, Too rich at idle, random misfire, misfire on cyl1, misfire on cyl 4, misfire on cyl 2. Since this all seemed related to the O2 sensor, I bought an OE Bosch one for $150 and replaced it. The same P0141 code is being thrown. The connectors are clean, I verified the connector is seated.

Where should I go from here? Some have suggested online replacing the number 1 O2 sensor as well, but at $200 I would want to make sure that was the answer first. Any ideas? Help!

 

The info at this link may be of some value:

https://www.autocodes.com/p0141_bmw.html

Two new sensors and the same code appears?

This suggests the sensors are ok the sensor connector/harness connector is not ok or the wiring is not ok.