NOx Sensor Supply Voltage Circuit (Bank 1 Sensor 1)
The supply voltage rail to the NOx sensor on bank 1 sensor 1 is faulty — typically a fuse, harness break, or short. NOx sensors need a clean stable supply for the heater and the wide-band measurement cell.
Affected components
- Nox sensor
- Nox sensor supply relay
Common causes
- High likelihood: Fuse, harness break, or short
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
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.