Hi don’t know if anyone can help.
I have a 2003 316ti compact (E46). The dreaded yellow check engine lamp came on this morning. When I scanned for codes with my ELM based reader and proscan software I got code P0030- which points to a problem with the heating circuit on the pre cat oxygen sensor.
I got under the car and found that the connector for the sensor was ok, no damaged cables or corroded contacts. I probed around and found battery volts (possibly heater supply) and a varying 0.450V possibly O2 sensor output. Also found what looked like a neat little test point under a removable plastic cover on the O2 sensor connector. Unfortunately I cannot find a wiring diagram for my car on the net.
Does anyone know what the pin allocations are for the oxygen sensor? The
O2 sensor has six wires & the connector has six pins but only five wires go back the loom. I did get about 94 Ohms resistance across two pins of the O2 sensor with it unplugged from the loom, which might suggest the heater element is ok. The car drives as normal. Once the fault code (DTC) is cleared it shows as a pending code immediately, if rescanned and after a few short drives the check engine lamp comes back on. The proscan software also suggests that the engine is running in an open loop mode and that it cannot get a reading from the pre cat O2 sensor, the post cat sensors gave a normal reading.
Clearly I could go out and buy a replacement O2 sensor in the morning but from experience I would like to test that the correct volts and signals are getting to and from the sensor first.
Any advice on the correct pinout for the sensor would be greatly appreciated......