Powertrain, generic (extended)

P2D1E Reductant System Leak Detected - Large Leak

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

DEF line pulled off or connector not latched after service
DEF line split by ice expansion or road debris
Cracked dosing valve body or blown seal at the exhaust
Cracked pump module housing in the tank unit

Symptoms

  • 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

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–1,200
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

reductant linesreductant injectorreductant pumpscr module

Related codes

P2D1DP202DP20E8P2BA8P2BAA

References: gsi.ext.gm.com, patents.google.com, law.cornell.edu.