OBD-II code · Powertrain (generic, extended)
P218F 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.
Is it safe to drive with P218F?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyDosing line or nozzle fully blocked
- PossiblePump dead
- Less likelyLine frozen at very low ambient temperature
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)
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–5 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Metering Unit, Reductant Pump, Reductant Injection Valve
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.