Guide
Check engine light: what to do first
A check engine light means the car's computer saw a problem it cannot fix by itself. It might be small, like a loose gas cap, or serious. The first hour is about telling the difference.
Steady or flashing?
A steady light means a problem was found. You can usually drive to a shop or parts store.
A flashing light means an active misfire that can damage the catalytic converter within minutes. Slow down, reduce load and get the car off the road soon. Do not keep driving at highway speed.
Check the easy things
Tighten the gas cap until it clicks. A loose cap is a common cause of an EVAP code, and the light can go off after a few drives.
Look at the temperature gauge and the oil light. If either is in the red, stop driving.
Read the code
Many parts stores read codes for free, and a basic scanner is cheap. Write down the code, for example P0420. Look it up on our code pages to see what it means, whether it is safe to drive and what the repair usually costs.
A code points to a system, not always a part. A P0420 does not always mean you need a new converter. Ask what test shows the part is the cause.
When to stop right away
Stop if the car is shaking hard, smells like burning, loses power, or the temperature gauge is climbing. Call for a tow instead of driving to the shop.
Updated 2026-10-28. Not a repair shop, estimates only.