My car continues to through a code for the driver side (left) pre cat O2 sensor. I have installed three different sensors, so I know the sensor an sensor wiring are not problem. I have used a data logger to see that I'm not getting a signal from the sensor. I have tested the continuity on the plug (sensor to car wiring harness) and all pins are making a connection.

My question is: Does anyone know if there is another plug somewhere in line from the O2 sensor to the ECU? Or is there another reason this may be happening.

Thanks in advance.

 

Vermin love to nibble on sensor wires as they are near the cats for warmth anyway...I don’t know if you have the capability to check continuity to the ecu but it is likely there is none if the sensor is ok...or....it is possible that it will take some drive cycles for the ecu to reset the cat sensor so it could be working and still show a fail until the ecu resets the self check.

 

No wiring issue between the plug and O2 sensor.

 

Are you using the correct sensor? The #1 sensors are wide band.

If you have the right sensor, a WAG is there is a leak in the exhaust system. Every time the local dealer Porsche tech had my Turbo's exhaust system out he always replaced the metal o-rings that sealed the exhaust and turbo together. He indicated often these would get reused and they do not seal well when reused.

 

Yes, I'm using the correct sensor. It's not a leak, there is no reading from the sensor when logging.

 

Does anyone have any idea or wiring diagram?