P0040 2007 FORD FUSION - Oxygen Sensor Signal Swapped Bank 1 Sensor 1 / Bank 2 Sensor 1
- Crossed HO2S harness connectors
- Crossed HO2S wiring at the harness connectors
- Crossed HO2S wiring at the PCM connectors
- Bank 1 Sensor 1 / Bank 2 Sensor 1 harness is open or shorted
- Bank 1 Sensor 1 / Bank 2 Sensor 1 circuit connectors (wrong connection)
- Faulty Engine Control Module (ECM)
Tech notesThe oxygen sensor connector might be connected incorrectly.
- Engine Light ON (or Service Engine Soon Warning Light)
P0040 2007 Ford Fusion DescriptionThe heated oxygen sensor (HO2S) monitor determines if the HO2S signal response for a fuel shift corresponds to the correct engine bank. The test fails when there is no response from the HO2S being tested.