P0036 VOLKSWAGEN - How will I know if it is the "Upstream" or "Downstream" O2 sensor?

Question

I recently scanned my '03 Jetta to find the P0036 HO2S Heater Control Circuit code. This is a problem with one of the heated oxygen sensors for the engine. I can replace it, no problem. I just need to know which one to replace. There is an "upstream" and a "downstream" sensor. Is there any way to tell which one has the problem? If not, does anyone know which one has failed more often historically on these cars?

 

Thanks,

Paul

Answer 1

HI there,

This is the downstream O2 sensor on bank 1. Downstream means AFTER the catalytic converter.