P0457
Evaporative Emission System Leak Detected (Fuel Cap Loose/Off)
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The P0457 code specifically points to a gross EVAP system leak that the vehicle's computer believes is caused by a loose or missing fuel cap. Unlike the more general leak codes (P0455, P0456), this code is designed to tell you that the most likely issue is right at the gas cap itself.
The first thing to do is check your gas cap. Make sure it's on and tighten it until you hear it click — most caps are designed to click once when properly seated. If you recently filled up and forgot to replace it, or didn't tighten it all the way, that's almost certainly the cause. After tightening or replacing the cap, you can clear the code with a scan tool, or simply drive for a few days and the light should turn off on its own once the EVAP system passes its self-test.
If tightening or replacing the gas cap doesn't fix the issue, there may be a problem with the filler neck (the tube where the cap seats) or other EVAP components. In that case, a mechanic can run a smoke test to locate the leak. This is one of the easiest and least expensive check engine codes to deal with — often costing nothing more than a new gas cap.
Severity
Symptoms
- •Check Engine light is on
- •Noticeable gasoline smell near the vehicle
- •Slight reduction in fuel economy
- •Gas cap may feel loose or fail to click into place
Likely Causes
The most common trigger is simply a gas cap that wasn't tightened until it clicked, was left off after refueling, or fell off.
Over time the rubber O-ring seal on the gas cap dries out, cracks, or deforms, allowing it to no longer create an airtight seal on the filler neck.
The metal or plastic filler neck where the gas cap seats can become corroded, bent, or cracked, preventing a proper seal even with a good cap.
A large crack in an EVAP vapor hose or the charcoal canister can mimic a fuel cap leak and trigger this code.
A stuck-open purge valve or vent valve can create a large enough leak to trigger this fuel-cap-specific code.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Tighten the gas cap until it clicks and clear the code
- Replace the gas cap with a new OEM-spec cap
- Inspect and replace the filler neck if corroded or damaged
- Perform a smoke test if the code persists after cap replacement
Shop Parts
Videos
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