Cylinder 3 Misfire Detected

What it means

The engine computer has recorded cylinder 3 repeatedly failing to fire. The driver usually feels shaking and weakness, and the most common cause is the spark plug, ignition coil or injector of that cylinder.

Related codes: P0300P0302P0304P0353P0203P0267

Symptoms4

• Engine shaking at idle and at low speeds.
• Reduced pulling power when moving off.
• Check engine light on, possibly flashing under load.
• Uneven exhaust sound.

Possible causes6

• Damaged or worn-out spark plug in cylinder 3.
• Weak ignition coil for cylinder 3 or a cracked coil boot.
• Cylinder 3 injector spraying poorly or not at all.
• Fault in the coil or injector wiring or connector.
• Vacuum leak near the cylinder 3 intake runner.
• Low compression from valves, rings or the head gasket.

How to diagnose5

1. Use the misfire counters on a scan tool to confirm cylinder 3 is the only or most affected cylinder.
2. Inspect the cylinder 3 plug; a fuel-wet plug suggests no spark, while a dry plug may suggest no fuel.
3. Swap the coil with another cylinder and see if the misfire moves.
4. Check that the cylinder 3 injector receives its signal and have an injector balance test done.
5. Have a compression test done and compare cylinder 3 with the others.

How to fix6

1. Replace the faulty spark plug, preferably the full set.
2. Replace the faulty ignition coil or its boot.
3. Repair the wiring or connector.
4. Clean or replace the injector.
5. Fix the vacuum leak or the cause of low compression, based on the test results.
6. Clear the codes, then road test and confirm the code does not return.

The low end covers a spark plug or coil, the high end an injector or an intake leak repair; low compression needs a separate estimate.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

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