Bank 1 Sensor 1 has been replaced twice in the last year....Both times the check engine light has come back on after the error code was errased. The VW dealer has now indicated that the problem is in the ECU. I'm skeptical, to say the least. I would like to follow the signal to the ECU if that's possible. The ECU to the O2 sensor has four wires: one Green, one brown/white, one brown, and one black. One pair supplies the 12volt for the sensors heater, and the other pair (?) I assume carries the sensing voltage back to the ECU. This sense voltage, I've been told, should be 0.1 to 0.9 volts D.C. when the sensor is operating properly. Is this true, and is this window constant, or does it need to move? All advise is greatly appreciated.
Thanks,
George