P0300 OBD-II code — what it means and what to check

ℹ Guidance only — not a substitute for inspection

Enter the trouble codes from your scanner to see what each one means, how urgent it is, and which checks to do first.

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Your trouble codes

Enter the codes exactly as your scanner shows them. Separate several codes with spaces or commas.

A letter followed by four characters, for example P0301. Up to ten codes at a time.
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Your codes, interpreted

What this means
⚠ Have this looked at now. At least one code you entered should not be left until the next service.
What to doArrange a workshop inspection now, and keep journeys short and local until then.

Your codes

  1. P0300 — Ignition (service now). The engine is misfiring, and the computer cannot attribute it to one cylinder. Fuel is not being burned properly somewhere, on more than one cylinder or unpredictably.

Checks to do first, in order

  1. If the warning light is flashing rather than steady, stop driving and have the vehicle recovered — a flashing light means unburned fuel is reaching the catalytic converter and destroying it.
  2. Check for other codes first: a lean, timing or sensor fault often causes misfire as a symptom.
  3. Inspect spark plugs, coils and leads.
  4. Have fuel pressure and vacuum leaks checked if ignition components are good.

Codes this tool cannot interpret

How this result was reached
  • Interpretations cover standardised codes only, and describe what a code means rather than what is wrong with your specific vehicle.
  • A stored code identifies the circuit or system reporting a fault. It does not identify the failed part — a sensor commonly reports a problem it did not cause.
  • Reviewed by Project Owner on 2026-08-26.
  • This tool covers a reviewed subset of standardised codes. A code it does not recognise is reported as undocumented rather than guessed at.