What would cause DTCs saying my "O2 sensor circuits have no activity detected" ?
Car is 2000 A4 Quattro ATQ 2.8L V6
Am getting 4 DTCs, one on each O2 Sensor; causes Check Engine Light to come on.
DTCs appeared suddenly and after erasing, they reappear in about 3 drive cycles.
All four O2 Sensors were new 2 years ago and are Bosch brand with OEM plugs.
Engine runs fine.
No blown fuses in LH dash fuse panel.
Tried powering-down (disconnecting) the ECM.
Initially had replaced Engine Coolant Temperature Sensor because was getting DTC P1114.