Now wasn't that easy??? If you have a scanner that can monitor the PID'S for the rear 02 sensors you can compare the voltage that the sensors are putting out. Rear 02 sensor will put out almost a constant voltage whereas pre-cat sensor voltage will be going up and down to adjust the fuel mixture.

Some time an OBDII diagnostic will provide more info than BMW specific diagnostic. You can just purchase an inexpensive Bluetooth scanner and use an App such as OBD Fusion or Torque to view live data.

YES SIR IT WAS...and thank you much. New Bosch on the way.

Did a new O2 sensor fix the issue? I’ve got a p1170 I can’t seem to shake. INPA gives me this error: 22 Lambda-Sensor ageing TV Bank2. Replaced rear driver’s side O2 with a BOSCH and still getting same code. Maybe the sensor was bad out of the box? I need to pull the O2 readings but I’m unsure of how to do that with the torque app. Keep us updated

You need to be on the real time data screen. Hold your finger on the screen until it ask you to add a new dial. Select a dial (I would select an analog and digital dial). Select the PID that represent the voltage for the Bank 2 sensor 2. Select a medium size dial. Boom you just added a dial. run the torque scanner and see what voltage the 02 sensor is out putting out. You can also add a dial for Bank 1 sensor 2 to compare the two 02 sensors. If they are the same than your problem is somewhere else.

I replaced the sensor yesterday with Bosch. Driving about 50 miles thus far and all seems great. I will keep you posted once I hit over 400 when light could possibly resurface.