9 documented codes across 51 real diagnostics.
The mixture the ECU cannot correct for. Lean codes (P0171) usually mean unmetered air or a leaking exhaust before the sensor. Seeing lean AND rich together points at the sensor, not the mixture.
Ranked by how often we actually see them
- P0171, System too lean, bank 1
- P0172, System too rich, bank 1
- P2178, System too rich off idle, bank 1
- P2187, System too lean at idle, bank 1
- P2177, System too lean off idle, bank 1
- P2188, System too rich at idle, bank 1
- P2181, Cooling system performance
- P0170, Fuel trim, bank 1
- P0174, System too lean, bank 2