P0457: Evaporative Emission System Leak Detected — Fuel Cap Loose or Off
What to do
Refit the fuel cap firmly until it clicks, and drive normally for a few days — the light will usually clear on its own once the system re-tests and passes. If it returns, replace the cap before paying for diagnosis.
What this code means
The module has concluded specifically that the fuel filler cap is loose, missing, or not sealing. Some systems can distinguish this from a general leak by noting that the fault appeared immediately after a refuelling event — the fuel level changed, and the system stopped holding pressure at the same moment.
It is worth taking the code at face value first, because it is right more often than not. If a correctly fitted cap does not clear it, treat the fault as an ordinary leak of unknown size and test accordingly; a cap that tightens with the usual clicks can still have a hardened seal.
Likely causes
Start here
- Loose or missing fuel filler cap · easy
- Perished fuel cap seal · easy
Less common
- Leaking filler neck seal · moderate
- Incorrect non-original fuel cap · easy
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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