O2 Sensor Circuit Malfunction (Bank 1 Sensor 3)
The ECU detects a general electrical fault on the third oxygen sensor in the bank 1 exhaust path (typically located after a second catalyst on diesel or large engines with multi-cat exhausts).
Affected components
- Oxygen sensor b1s3
- Oxygen sensor wiring
Common causes
- High likelihood: Sensor aged or failed
- Medium likelihood: Sensor wiring open or shorted
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.