NOx Sensor Performance Signal Biased or Stuck High Bank 1 Sensor 3
The NOx sensor on bank 1 sensor 3 reports a value that stays at the upper end of its range despite changing engine conditions - sensor element biased or stuck high.
Affected components
- Nox sensor b1s3
Common causes
- High likelihood: Sensor element biased high
- Low likelihood: Sensor element aged beyond calibration window
- Low likelihood: Sensor element contaminated by oil, soot or coolant
Possible symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
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.