P2278 Possible Causes
- Faulty O2 sensor
- O2 sensor harness is open or shorted
- Poor electrical connection in the O2 sensor circuit
What Does It Mean?
How to Fix Code P2278
Check the “Possible Causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
P2278 Symptoms
Check engine light on (or service engine soon warning light)
P2278 Meaning
O2 sensor signals swapped, bank 1, sensor 3 / bank 2, sensor 3 is the generic description for code P2278, but the manufacturer may have a different description.