NOx Sensor Circuit Low (Bank 1)
The NOx sensor signal on bank 1 is below the lower limit. Either short to ground on the analog return, sensor failed at low end, or pump cell stuck.
Affected components
- Nox sensor
- Nox sensor wiring
Common causes
- High likelihood: Signal wire shorted to ground
- Medium likelihood: Sensor failed low
- Low likelihood: Connector pins corroded - high contact resistance
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
- 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.