P220A — 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.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Nox sensor
- Nox sensor supply relay
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- 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
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
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.