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ENRUDEPLES

P0301 — Cylinder 1 Misfire Detected

serious

What it means

The control module has recorded misfires localised in cylinder 1: the mixture in that cylinder is not burning, or burns incompletely. It is detected from the momentary drop in crankshaft angular speed on that cylinder power stroke and shows up as vibration, rough idle and loss of power. The unburned mixture goes into the exhaust, so the catalytic converter overheats and the oxygen sensor readings are distorted.

Likely causes (most common first)

  1. Worn or fouled spark plug in cylinder 1
  2. Failing ignition coil or high tension lead on that cylinder
  3. Clogged, leaking or electrically faulty injector in cylinder 1
  4. Unmetered air leak at that intake runner or a damaged injector seal
  5. Low compression in the cylinder: burnt valve, worn rings, valve clearance out of specification
  6. Damaged wiring or connector at the coil or injector of cylinder 1, or a leaking head gasket at that cylinder

Can you drive with it?

Short trip to the workshop only, and if the check engine lamp is flashing stop immediately: raw fuel is burning out the catalytic converter.

This is the generic meaning. What about your car?

The same code has different typical culprits on different engines. Tell the AI your make, model and year — it will rank the causes for your exact car and give you a check order.

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