Check Engine Light On? What to Do Next

The check engine light, sometimes shown as an engine outline, signals that the car's onboard diagnostic system has detected a fault in the engine, emissions, or related systems.

It does not always mean the car is about to break down, but it should not be ignored.

Steady vs flashing

▸A steady light usually means a fault that should be checked soon
▸A flashing light often indicates a serious misfire that can damage the catalytic converter; reduce speed and have the car checked promptly

Simple checks

▸Make sure the fuel cap is tightened properly
▸Notice any changes in how the car runs, such as rough idle, loss of power, or poor fuel economy
▸Check for other warning lights

Read the code

A diagnostic scan reads the stored trouble codes. Many parts stores and garages offer this, and affordable OBD-II readers are available for most modern cars.

Common causes

▸Oxygen sensor faults
▸Spark plug or ignition coil problems
▸Mass airflow sensor issues
▸Evaporative emissions system leaks
▸Catalytic converter problems

Do not ignore it

A code points towards a system, not always to the exact part. Have a qualified technician diagnose the cause before replacing parts.

CAUTION: This is general automotive information, not professional mechanical advice. Always follow your vehicle manufacturer’s specifications and service schedule, and have brakes, steering, tyres, and other safety-critical systems inspected by a qualified mechanic.

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