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

P02B9 Cylinder 8 - Injector Leaking

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. P02B9 means the module detects fuel entering cylinder 8 outside the injection pulse – the injector is leaking or dripping. A BMW patent identifies such a leak by the fact that it persists with the injector switched off. A leaking diesel injector can dilute the oil or damage the piston, so act promptly. 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

Nozzle seat or needle of the cylinder 8 injector leaking
Deposits keeping the needle from closing fully
Rail pressure too high
Wrong or wrongly coded injector

Symptoms

  • Check engine light on
  • Rough idle, vibration
  • Smoke, fuel smell, knocking

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 8crankshaft position sensorengine control module

Related codes

P02B6P02B7P02B8P0284P02DAP0172

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