P2D1EReductant System Leak Detected - Large Leak
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2D1E is the severe form of the DEF leak verdict: the pump cannot build or hold working pressure because fluid escapes freely, for example from a split or disconnected line. No manufacturer documents this code publicly. GM's 2025 diesel tables catch the same physical result under P20E8, which fails when measured DEF pressure stays more than 63 kPa below its setpoint for 30 s with over 3 litres in the tank (Type A, MIL on the first trip). California requires the reductant delivery system to be monitored, and a leak of this size stops dosing, so NOx conversion collapses. Unlike P2D1D, fluid is often visible as a puddle or wet trail. Most trucks soon start the service countdown toward a speed limit.
- What you may notice
- Check engine light and DEF system warning soon after start
- Puddle or wet trail of DEF under the vehicle
- Countdown to restricted speed or no restart
- Likely causes
- LikelyDEF line pulled off or connector not latched after service
- LikelyDEF line split by ice expansion or road debris
- PossibleCracked dosing valve body or blown seal at the exhaust
- RareCracked pump module housing in the tank unit
- 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 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.