Reductant Leakage
A leak has been detected in the DEF (urea) supply system — usually by a pressure-decay test after pump shutdown, or by visible crystallisation around fittings.
Affected components
- Reductant supply line
- Reductant pump
- Reductant injection valve
Common causes
- High likelihood: Cracked DEF line or fitting
- Medium likelihood: Pump seal leaking
- Medium likelihood: Injector mounting seal leaking
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.