O2 Sensor Signals Swapped Bank 1 Sensor 1/Bank 2 Sensor 1
The pre-cat oxygen sensors of bank 1 and bank 2 appear to be wired the wrong way around — bank 1 reacts when bank 2 should and vice versa. Typically after recent service.
Affected components
- Oxygen sensor b1s1
- Oxygen sensor b2s1
- Sensor wiring
Common causes
- High likelihood: Sensors swapped after recent replacement
- Medium likelihood: Wiring harness routed across banks
Possible symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.