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

P02D3 Cylinder 4 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. P02D3 means the learned correction for cylinder 4 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. GM diesels set it at limits of roughly ±66–182 µs after two trips. Older GM calibrations (LML) use only this code of the pair, for both directions. It is documented on GM's 6.6 litre L5P and 2.8 litre diesels – on the 2.8 a worn drive belt caused it to return after injector replacement – and on Land Rover's 5.0 V8 petrol, where a software update is the first step. It differs from P01D1 (over retarded), which some systems derive from the same learning.

Likely causes

Injector of cylinder 4 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 4crankshaft position sensorengine control module

Related codes

P02D2P01D1P020DP0272P0204P026C

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov.