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P0304
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Powertrain (Engine)
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Basic OBD2 code reader (engine codes, live data, smog readiness)

Cylinder 4 Misfire Detected

Understand P0304, common causes, and the right TOPDON scanner to diagnose it.

The ECU detected repeated misfires on cylinder 4 only. Unlike P0300 (random/multiple misfire), P0304 points to a specific cylinder — spark, fuel, or compression on that bore.

Veelvoorkomende symptomen

  • Rough idle that may feel rhythmic
  • Loss of power under load
  • Check engine light (steady or flashing)
  • Possible fuel smell from unburned fuel

Typische oorzaken

  • Worn spark plug or failed ignition coil on cylinder 4
  • Clogged or leaking fuel injector for cylinder 4
  • Low compression on cylinder 4 (valve, ring, or head gasket)
  • Vacuum leak affecting one runner (intake gasket, cracked hose)
  • Loose or damaged coil-on-plug boot on cylinder 4

Welke scanner heb je nodig?

Basic OBD2 code reader (engine codes, live data, smog readiness)

Gebruik live data en freeze frame voordat je onderdelen vervangt. ABS-, SRS- en U-codes vereisen meestal een full-system scanner.

Diagnosetips

  • Leg freeze frame vast wanneer de code voor het eerst verschijnt
  • Wis de code pas na het oplossen van de oorzaak
  • Controleer op gerelateerde pending codes
  • Controleer of accuspanning boven 12,4 V is voordat je sensoren suspecteert

Aanbevolen TOPDON scanners

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Veelgestelde vragen

What does P0304 mean?
P0304 indicates cylinder 4 misfire detected. The ECU detected repeated misfires on cylinder 4 only. Unlike P0300 (random/multiple misfire), P0304 points to a specific cylinder — spark, fuel, or compression on that bore.
Can I diagnose P0304 with a basic code reader?
Yes — P0304 is typically accessible with a basic OBD2 code reader like the TOPDON ArtiDiag201 or TopScan Lite. Live data helps confirm the repair.
Which TOPDON scanner do I need for P0304?
Basic OBD2 code reader (engine codes, live data, smog readiness) See recommended tools on this page.
Is it safe to drive with P0304?
It depends on the code and symptoms. Flashing check engine lights and misfire codes should be addressed immediately. Consult a professional if unsure.