I learned something about our cars recently and wanted to share this as it may relate to some problems others may have. Recently I welded up my own exhaust, designed to enhance the sound. It was a success but in the process, I probably knocked loose a lot of crap that I believe got into the rear sensors and after putting things together, I started to get a lean status on Bank 1 sensor 2. I reversed the connectors and got lean on Bank 2 sensor 2. Then it quickly became No signal Bank 1 Sensor 2. Anyway I ordered 2 new Bosch sensors, got them in 3 days and installed. Feeling that things would be all right I took the Ghost out for a drive. Oops, CEL came on. When I got home I checked it and found Bank 1 Sensor 2 rich. After a little thought I decided that the CPU was still trying to make adjustments for the lean and no signal conditions, so I erased the codes and started to drive it again. After a day, I got the same code, so I erased it again and have not had it since. The CPU learned that I had replaced the sensors and eventually adjusted to the conditions. My point is, if you correct a problem, remember to give the computer a chance to adapt to the new conditions.