P0040
Powertrain Codes
P0040 - BMW - O2 Sensor Signal Wires Swapped- HO2S11 with HO2S21
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
Possible Causes
- HO2S11 and HO2S21 sensors harness circuit shorted - HO2S11 and HO2S21 sensors harness circuit connectors (wrong connection) - Faulty Engine Control Module (ECM)
Description
The heated oxygen sensor (HO2S) monitor determines if the HO2S signal response for a fuel shift corresponds to the correct engine bank.