NOx Sensor Circuit Range/Performance Bank 1 Sensor 2
The downstream NOx sensor on bank 1 (after the SCR catalyst) returns implausible NOx readings during operation. Either the sensor is degraded or upstream chemistry is abnormal.
Affected components
- Nox sensor
- Scr catalyst
Common causes
- High likelihood: NOx sensor aging
- Medium likelihood: Low SCR efficiency
- Low likelihood: Sensor element aged beyond calibration window
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
- Reduced-power or limp mode may occur
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.