CKFCar Known Faults
P0300severe Severity

Random/Multiple Cylinder Misfire Detected

The Engine Control Module (ECM) has detected a misfire occurring randomly or across multiple cylinders. A misfire means the air/fuel mixture in the cylinder is not burning properly.

Common Symptoms

  • Flashing Check Engine Light (CEL)
  • Rough idle or shaking
  • Hesitation or jerking under acceleration
  • Strong smell of unburnt fuel from the exhaust

Generic Causes

  • Worn or fouled spark plugs
  • Failing ignition coil packs
  • Vacuum leaks
  • Low fuel pressure or failing fuel injectors

Known Cars Affected by P0300

We have cross-referenced P0300 against our database of known faults. Below are specific cars where this code frequently appears, along with the detailed diagnostic and repair instructions for that specific vehicle.

Carbon Build-Up on Intake Valves

Moderate
2006-201340,000–80,000 miles£300–£600

The N14's direct injection system means fuel is injected directly into the cylinder, bypassing the intake valves. Oil vapour from the PCV system coats the valves with carbon, causing power loss and misfires.

Ignition Coil Pack Failure

Moderate
2002-200840,000–90,000 miles£80–£120

The single coil pack block fails, causing a 2-cylinder misfire.

Carbon Build-up on Intake Valves

Moderate
2006-201040,000–80,000 miles£200–£350

Because the N14 is a direct-injection engine, fuel does not wash over the intake valves. Oil vapor from the PCV system bakes onto the hot valves, causing severe carbon build-up.

Coil Pack Failure and Misfires

Moderate
2014-201940,000–90,000 miles£150–£200

The ignition coil pack on the 1.4 engine frequently fails, causing severe misfires, sluggish performance, and a flashing engine management light.

Ignition Coil Pack Failure

Moderate
2014-201950,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2012-201950,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2008-201750,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2005-201150,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2008-201550,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2012-201950,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2012-201750,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2011-201850,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2005-201450,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2006-201250,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2006-201350,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2008-201250,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2007-201950,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2010-201950,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.

Ignition Coil Pack Failure

Moderate
2006-201450,000–100,000 miles£50–£150

Coil packs break down internally with heat and age, causing severe misfires under load.