Random or Multiple Cylinder Misfire Detected

What it means

The engine computer has detected incomplete combustion in more than one cylinder, with no fixed pattern. This usually points to something shared by all cylinders, such as fuel delivery, a vacuum leak or worn spark plugs, rather than one faulty part.

Symptoms5

• Noticeable shaking, especially at idle or under acceleration.
• Loss of power and hesitation when pressing the throttle.
• Check engine light on, possibly flashing during severe misfires.
• Higher fuel consumption.
• Smell of raw fuel from the exhaust.

Possible causes7

• Worn spark plugs across all cylinders.
• Vacuum leak from cracked hoses or a leaking intake gasket.
• Low fuel pressure from a weak pump or clogged fuel filter.
• Dirty injectors or poor-quality fuel.
• One or more weak ignition coils.
• A faulty mass airflow sensor giving wrong readings.
• Low compression or incorrect engine timing (less common).

How to diagnose and fix7

1. Check for other stored codes, since they often reveal the root cause.
2. Inspect the spark plugs and replace them if they are due.
3. Listen for hissing and inspect vacuum hoses for leaks.
4. Measure fuel pressure against the specification.
5. Swap coils between cylinders to see whether the misfire follows a coil.
6. Clean the mass airflow sensor with a dedicated cleaner.
7. If misfires persist, have a compression test done.

Repair cost

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

The cost can be low if plugs or a vacuum hose are to blame, and climbs when the fuel pump, injectors or internal engine wear are involved.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.

Frequently asked questions