Powertrain, generic · Fuel and air metering (injector circuit)

P02DD Cylinder 9 Fuel Injector A Offset Learning At Max Limit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The engine module learns a small-quantity correction for each injector: on overrun it gives one injector a tiny test injection (GM about 1.5 mm³), measures the resulting crankshaft acceleration and corrects the injector's activation time per rail pressure step. P02DD means the learned correction for cylinder 9 has reached its upper limit at at least one pressure step: the injector needs much more activation time than nominal – it delivers too little or opens late, for example from coking. Cylinder 9 exists only on ten-cylinder engines; no manufacturer using this code was found, so the description follows CARB and the documented codes for cylinders 1–8. It differs from P01DB (over retarded), which some systems derive from the same learning.

Likely causes

Injector of cylinder 9 coked or worn (delivers too little)
Engine software (update available for some models)
Injector correction code not or wrongly programmed after replacement
Disturbed crankshaft signal (worn drive belt, tone wheel, dual-mass flywheel)
Low compression on this cylinder

Symptoms

  • Check engine light on
  • Often nothing noticeable; possibly rough idle or knocking
  • Possibly smoke or loss of power

Repair estimate

DifficultyHardWorkshop job
Parts and labour€0–1,200
Time0.5–4 h

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

Parts involved

fuel injector cylinder 9crankshaft position sensorengine control module

Related codes

P02DCP01DBP021CP0287P0209P026C

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