Reductant Injection Air Pressure Sensor A/B Correlation
The two reductant injection air-pressure sensors A and B disagree by more than the allowed tolerance — one is reading off, or there is a real pressure imbalance between the two air-assist branches.
Affected components
- Reductant air pressure sensor
- Reductant air pump
Common causes
- High likelihood: One sensor drifts relative to the other
- Medium likelihood: Real imbalance between air branches
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.