Powertrain
generic / SAE
P20F4
Reductant Consumption Too Low
The DEF consumption observed over the dosing window is below the model expectation — typically a clogged dosing nozzle, weak pump, or leak between pump and injector that recirculates DEF back to the tank.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number– / F4
Possible causes
- Dosing nozzle clogged with crystallised DEF high
- Pump weak — flow under target medium
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)
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 200–1500 €
- Estimated time: 1–4 h
- Component: reductant metering unit
- Component: reductant pump
- Component: reductant injection valve
- MIL / check engine light
- emissions-relevant
- drive cycle required
Sources
References
sae:J2012