What does it mean when the check engine light comes on?
The check engine light means the engine computer saved a trouble code. It can be anything from a loose gas cap to a misfire.
Most likely causes
- Loose gas cap. Triggers EVAP codes like P0442 or P0455.
- Misfire. Codes P0300–P0308. A flashing light means an active misfire.
- Oxygen sensor or catalytic converter. Codes like P0420.
- Vacuum leak or air sensor. Codes like P0171 and P0174.
Simple things to check
- Tighten the gas cap
- Get the code read for free at many auto parts stores
- Note whether the light is steady or flashing
When to stop driving
A flashing check engine light means stop driving soon — it can damage the catalytic converter.
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