987 · Engine

P0301

Cylinder 1 Misfire Detected

MED SEVERITY

The DME detected a misfire on cylinder 1 (bank 1, cylinders 1-3). On the flat-six, coil packs and spark plugs are the most common cause. On 987.2 DFI engines, injector and carbon issues also contribute.

SYMPTOMS

  • Rough idle
  • Check-engine light (may flash)
  • Loss of power
  • Hesitation

LIKELY CAUSES

  • Failed ignition coil
  • Worn spark plug
  • Fuel injector fault
  • Vacuum leak
  • Low compression

DIAGNOSIS STEPS

  • Read freeze-frame data
  • Swap the coil/plug to an adjacent cylinder and see if the misfire follows
  • Inspect the injector
  • Compression/leak-down test if it persists

RELATED PARTS

  • Ignition coil
  • Spark plug
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