Cylinder 8 Misfire Detected

What it means

The engine computer has recorded cylinder 8 repeatedly failing to fire; on most engines that set it, this is the last cylinder of a V8. The most common cause is its spark plug, ignition coil or injector.

Related codes: P0300P0307P0306P0358P0208P0282

Symptoms4

• Stumbling or shaking at idle.
• Weak acceleration or pulling power.
• Check engine light on or flashing.
• Higher fuel consumption.

Possible causes6

• Damaged spark plug in cylinder 8.
• Weak ignition coil or damaged plug wire for cylinder 8.
• Clogged or faulty cylinder 8 injector.
• Wiring or connector damage from heat or chafing.
• Vacuum leak near this cylinder's intake runner.
• Low compression in the cylinder (less common).

How to diagnose5

1. Locate cylinder 8 using the manufacturer's numbering.
2. Watch the misfire counters; if cylinders 7 and 8 both misfire, look for a shared cause on that bank or in the wiring.
3. Inspect the plug, and swap the coil or wire with another cylinder to see whether the misfire moves.
4. Check the injector, its signal and its connector.
5. Have a compression test done if the cause is not found.

How to fix6

1. Replace the spark plug, or the full set if it is due.
2. Replace the faulty ignition coil or plug wire.
3. Repair damaged wiring or connectors.
4. Clean or replace the injector.
5. Repair low compression if confirmed.
6. Clear the codes, road test and confirm the code does not return.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

The low end is a plug or coil; the high end is an injector or difficult access to the cylinder on larger engines.

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

Frequently asked questions