O2 Sensor Output Question

[Chisum]

I have a 2003 525 that is running great but the other day I felt a stumble in the engine so I pulled out the old Peak reader to check if I had any codes recorded. The car had a stored 19E4 code "O2 sensor adaptation limit Cyl # 4-6". I loaded up TORQUE and can see the O2 sensor for Cyl 4-6 is flat-lined. I've replaced the O2 sensor but TORQUE still shows the O2 sensor for Cyl 4-6 is flat-lined. I'm not getting any other codes and the car is running fine. What could be causing a rich reading on Cy 4-6?

Chisum

[edjack]

The post-cat sensor (1-2) doesn't bounce around like the pre-cat sensor (1-1), since it's only monitoring cat output.

How did you determine that there is a rich reading on 4-6? What are the fuel trim numbers? If rich, the numbers s/b negative (the ECU is trying to compensate).

[Chisum]

The graph is showing the precat sensors. O2 1X2 should look just like O2 1X1. A high voltage output from an O2 sensor is a rich reading. The only thing I can think of that may cause a rich reading from the precat O2 sensor on banks 4-6 is a stuck injector. But I should be getting other codes if that were the case. Other then the "O2 sensor (http://forums.bimmerforums.com/forum/#) adaptation (http://forums.bimmerforums.com/forum/#) limit Cyl # 4-6" I'm getting the car runs great, hell the check engine light is not even turning on.

Chisum

[rf900rkw]

As Ed said, watching and complaining about bank 1 sensor 2 is not going to tell you anything about bank2 sensor 1. Get the right sensors on the screen and see what you get. 1x1 and 2x1.