P218FReductant No Flow Detected
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P218F means the SCR system is dosing on paper, but nothing reaches the exhaust: the expected link between dosing commands, pump effort and line pressure is missing. Ford's 2023 diesel summary, which calls the test a reductant delivery check for clogging, runs it while dosing with the pressure error inside 0.5 bar for 5 s. It fails when the pressure barely reacts to changes in the injection rate and the mix of rate and pump duty misses its model by more than 0.15. Ford also lists it for the 6.7 L Power Stroke (18-2127, PCM update). Nissan reflashed Titan XD trucks with the Cummins 5.0 L V8 when P218F appeared at 0 °C or below. VW says P218F can stay after repairs on 2.0 TDI cars until a leak in the DEF line is fixed. Pressure codes are P20E8/P20E9.
- What you may notice
- Check engine light with a DEF or emission system warning
- Restart countdown or speed limitation if the fault persists
- DEF consumption lower than usual
- White crystalline deposits at the dosing valve or line joints
- Likely causes
- LikelyDosing valve or its nozzle crystallised and blocked
- PossibleLeak in the DEF line between pump and dosing valve
- PossiblePartly frozen line in frost or control software that needs an update
- RareWorn DEF pump that cannot keep up delivery
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €0 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.