The check engine light is part of your vehicle's onboard diagnostic system. When a sensor detects a problem with the engine, emissions, or related systems, it stores a trouble code and turns on the light.
Solid vs. flashing
A solid light means something needs attention soon, but it's usually safe to keep driving carefully until you can get it checked. A flashing light typically signals an active engine misfire that can damage the catalytic converter. If it's flashing, reduce speed and have the vehicle inspected as soon as possible.
Common causes
Some of the most frequent reasons the light turns on include:
- A loose or damaged gas cap
- A failing oxygen sensor
- Worn spark plugs or ignition coils
- A faulty mass airflow sensor
- Catalytic converter issues
Why a code alone isn't the full answer
A trouble code points to the system that reported the problem, not always the root cause. Professional diagnostics combine the code with testing and inspection so you only pay for the repair you actually need.
