O2 Sensor Circuit Range/Performance Bank 1 Sensor 4
The fourth oxygen sensor on bank 1, where present, returns implausible values during long-term plausibility evaluation. Used on multi-stage aftertreatment systems.
Affected components
- Oxygen sensor
Common causes
- High likelihood: Sensor aging
- Low likelihood: Sensor element aged beyond calibration window
- Low likelihood: Sensor mounting loose - signal damping
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.