Error code

OBD2 P0309

OBD2P0309
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Cylinder 9 Misfire Detected.

Severity

moderateCan be driven, but performance will suffer and it may cause additional damage if not addressed.

Summary

P0309 indicates that cylinder number nine in the engine is misfiring. This issue can be detected by the crankshaft position sensor and camshaft position sensor.

Symptoms

  • Vibrations at idle
  • Decreased engine performance
  • Reduced fuel economy

Common Causes

  • Faulty cylinder #9 spark plug
  • Faulty cylinder #9 coil
  • Faulty cylinder #9 wiring
  • Faulty cylinder #9 fuel injector

Diagnosis

  1. Check for a technical service bulletin related to the issue
  2. Swap ignition components between cylinder #9 and another cylinder to identify faulty parts
  3. Inspect compression issues, such as exhaust valve or head gasket leaks

Fixes

  • Replace faulty spark plug, coil, wiring, or fuel injector in cylinder #9

FAQ

What does P0309 mean?

P0309 indicates a misfire in cylinder number nine of the engine.

How do I diagnose P0309?

Diagnose by swapping ignition components and checking for compression issues.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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