Powertrain, generic (extended)

P20D2 Exhaust Aftertreatment Fuel Injector B Control Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

With its wiring intact, the second exhaust fuel doser (B) is not delivering what was asked for: too little heat appears across the catalyst during dosing, or heat appears when it should be idle. No manufacturer documents P20D2 publicly. The comparable check for injector A on GM's 6.6 L Duramax (P20CC, 15OBDG09) watches for the catalyst outlet running far hotter than its inlet outside regeneration. CARB requires a malfunction whenever the injection system can no longer bring about regeneration, and a feedback-control fault if the system runs out of adjustment. Stuck positions of doser B are P20D5 and P20D6, the electrical faults P20D1, P20D3 and P20D4.

Likely causes

Partly coked nozzle on doser B
Low or unstable fuel pressure feeding doser B
Exhaust temperature sensor reading wrong

Symptoms

  • Check engine light on
  • Longer or more frequent regenerations
  • Higher fuel consumption

Repair estimate

DifficultyHardWorkshop job
Parts and labour€300–1,500
Time1–3 h

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

Parts involved

aftertreatment fuel injector

Related codes

P20CCP20D1P20D5P20D6

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