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

P02A8 Cylinder 4 - Injector Restricted

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

These codes belong to an individual-cylinder fuel correction: a diesel's cylinder balance control measures each cylinder's crankshaft acceleration and adjusts its injection quantity; on petrol engines a cylinder-selective mixture control does the same. CARB requires the system to report when such a correction has used up its range or one cylinder causes an imbalance. P02A8 means the module attributes the deviation of cylinder 4 to an injector delivering too little – deposits or a sticking nozzle needle. GM's 2.8 litre Duramax lists it as a stuck-injector fault in its cylinder balance system, which then switches the balance control off. GM and Ford use other codes for this (P0263 ff, P219A ff); no manufacturer document describing this code with thresholds was found, so the description follows CARB and published patents.

Likely causes

Deposits or coking at the nozzle of cylinder 4
Nozzle needle sticking
Contaminated fuel or water
Injector circuit high-resistance
Compression loss mimicking low output

Symptoms

  • Check engine light on
  • Rough idle, vibration
  • Lack of power, higher consumption or smoke

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€150–900
Time1–4 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

P02A6P02A7P02A9P0272P02D3P0204

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