A check engine light after getting gas often points to the gas cap. If the cap is loose, cracked or worn, fuel vapour leaks out. The car’s evaporative emissions (EVAP) system spots the leak and turns on the light.
One US mechanic says a loose or missing gas cap causes about 10% of all check engine lights.
Start with the cap. Make sure it’s on tight and turn it until it clicks. The light can stay on for a few drive cycles before it goes out.
If the light stays on, the cap may need replacing, or the leak may be somewhere else. Small leaks in EVAP hoses or valves can set off the same light. A scan tool reads the stored code, so you know where to look.
A flashing light, rough running or a loss of power is a different story. That isn’t a gas cap problem, so stop and get help.
If the light won’t clear, our mechanics can read the code and look for the leak. For prices, read our guide to check engine light diagnostic cost in Vancouver.
Service desk The full guide
Check engine light diagnostic cost in Vancouver: the published prices, what a quote covers and how to compare quotes.