O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3)
The ECU detects an abnormally low voltage from the third O2 sensor on bank 1. Indicates persistently lean exhaust, an open sensor or wiring shorted to ground.
Affected components
- Oxygen sensor b1s3
- Oxygen sensor wiring
Common causes
- High likelihood: Lean exhaust (vacuum leak, low fuel pressure)
- Medium likelihood: Signal wire shorted to ground
- Medium likelihood: O2 sensor failed
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.