P2D1DReductant System Leak Detected - Small Leak
- 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
- P2D1D reports that the pressurised DEF (AdBlue) circuit between pump, line and dosing valve loses fluid slowly, too little to collapse pressure but enough to be measurable. No manufacturer documents this code publicly. A supplier patent from Plastic Omnium shows how such leaks are found: with dosing at zero the pump should idle near 1,500 rpm at 5 bar, and a speed above 1,750 rpm raises suspicion; the line is then drawn into vacuum and a rise above -200 mbar within about 20 s confirms the leak. California requires reductant delivery to be monitored. P2D1E is the large leak, P202D the older general leakage code. Expect white crystal crusts at fittings, higher DEF use and, if ignored, an SCR warning.
- What you may notice
- Check engine light, usually with an exhaust service message
- White crystalline deposits at line fittings or the dosing valve
- DEF consumption noticeably higher than usual
- Likely causes
- LikelySeeping quick connector or damaged O-ring on the DEF pressure line
- PossibleWorn seal or gasket at the DEF dosing valve on the exhaust pipe
- PossibleHairline crack in the DEF line, often after freezing or chafing
- RarePump module leaking internally or at its housing seal
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.