Hi, I have p0141 and p0140 codes popping up for secondary o2 sensor. I've already been through 2 o2 sensors. the car is an 02 1.8t.

Does anybody know what the readings are supposed to be from the 2 sensor heater wires on the ecu side of the plug?

Should I try replacing the primary o2 sensor? I read somewhere that the ecu can't really determine which o2 sensor is the problem when it comes to heater circuits.

Any help is appreciated, thanks