A: It sounds like a loose gas cap may have caused a diagnostic trouble code P0440 or similar to be recorded. However, there are dozens, if not more than a hundred, other reasons the check engine ...

While it might seem like a straightforward warning light to fix, seeing "Check Fuel Cap" on your dashboard could be a sign of something far more serious.

A “Check Engine” light on your dashboard could mean anything from a loose gas cap to a wallet-destroying repair in the offing. For [Dean Segovis], his CEL was indicating a fairly serious ...

RAY: That's because a poorly fitting or loose gas cap allows fuel vapors to escape into the atmosphere, which creates smog, which turns Los Angeles into Beijing.

It might not be on your list of regular car maintenance tasks, but it's important to keep your gas cap clean and ensure it's functioning properly.