Fuel Cap Warning
The gas cap is loose or missing — tighten it until it clicks. Often appears before a check engine light.
What it means
The evaporative emissions system detected a large vapor leak, and a loose fuel cap is by far the most common cause — so many cars show this dedicated warning first. Ignoring it will typically graduate to a check engine light with an EVAP code.
Can you keep driving?
Yes — but tighten the cap at the next stop. The light can take a few drive cycles to go out afterward.
What to do now
- 1
Remove the cap and refit it, turning until it clicks at least once.
- 2
If the cap's tether or seal is damaged, buy the correct replacement — cheap universal caps often still leak.
- 3
If the light persists for several days with a good cap, have the EVAP system smoke-tested.
Likely causes
- • Cap loose or not clicked (most common)
- • Cap left at the gas station
- • Cracked cap seal
- • Other EVAP leak (if a new cap doesn't fix it)
Typical fix cost
$0 to tighten; $10–$30 for a new cap
Ranges reflect mainstream US parts-and-labor pricing; your vehicle and region will vary.