Check Engine Light

What it means

The engine computer has detected a fault in the engine, exhaust or emissions system and stored a trouble code. A steady light usually means the issue is not urgent but should be checked soon, while a flashing light points to a severe misfire that can damage the catalytic converter.

Symptoms5

• The light stays on steadily after the engine starts.
• The light flashes while the engine shakes or loses power.
• Fuel consumption rises noticeably.
• Rough or unstable idle.
• A fuel smell or rotten egg smell from the exhaust.

Possible causes6

• A loose or damaged fuel cap.
• A weak or failed oxygen sensor.
• Worn spark plugs or a failing ignition coil causing misfires.
• A vacuum leak in the intake hoses.
• A dirty or faulty mass airflow sensor.
• A clogged or inefficient catalytic converter.

How to diagnose and fix6

1. Make sure the fuel cap is tight and watch the light over a few drives.
2. Read the trouble code with a scan tool to find the affected system.
3. Inspect spark plugs and coils if the code points to a misfire.
4. Check intake hoses for cracks or a hissing sound.
5. Clean the airflow sensor or replace the oxygen sensor as diagnosed.
6. If the light is flashing, slow down and head straight to a workshop to protect the catalytic converter.

Repair cost

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

Costs start low when the cause is a fuel cap or spark plugs, and climb sharply if the catalytic converter must be replaced.

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

Frequently asked questions