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

P02A6 Cylinder 4 - Fuel Trim at Max Limit

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. P02A6 means the correction for cylinder 4 is at its upper limit: the module keeps giving this cylinder more fuel and still cannot even it out – a sign that the cylinder receives too little fuel or builds too little pressure. 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

Injector of cylinder 4 coked or partly clogged
Compression loss in this cylinder (valve, rings, leak at injector or glow plug)
Injector circuit high-resistance or connector
Petrol: false air at this cylinder's intake (manifold gasket)
Injector correction code missing or wrong after replacement

Symptoms

  • Check engine light on
  • Rough idle, vibration
  • Lack of power, possibly misfire

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–900
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

P02A7P02A8P02A9P0171P0272P02D3

References: law.cornell.edu, patents.google.com, patents.google.com.