Reductant No Flow Detected
The DEF dosing system commands flow but the pressure or flow sensor reports no actual delivery — typically a fully blocked dosing nozzle, a frozen line, or a dead pump.
Affected components
- Reductant metering unit
- Reductant pump
- Reductant injection valve
Common causes
- High likelihood: Dosing line or nozzle fully blocked
- Medium likelihood: Pump dead
- Low likelihood: Line frozen at very low ambient temperature
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
- 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.