EVAP leak detected (fuel cap loose/off)
What P0457 means
Your car's computer set P0457: EVAP leak detected (fuel cap loose/off). It belongs to the emission controls group of codes. It is a generic code, so it means the same thing on every make. The check engine light usually comes on once the fault has been seen on two drives in a row. Until then it shows up as a pending code.
Can I keep driving? Usually safe to drive. The car may run normally, but it will not pass an emissions test until this is fixed.
Common causes
- Loose, worn or wrong gas cap
- Cracked EVAP hose
- Leaking purge or vent valve
- Leaking filler neck
Fix the cheapest, most likely cause first. Clearing the code without a repair only turns the light off until the fault comes back.
Check it yourself
Tighten the gas cap until it clicks, or replace it, then drive a few days. The code often clears by itself.
Torque Deck reads P0457 with a cheap Bluetooth OBD2 adapter. It also shows the freeze frame (engine conditions at the moment the code set) and the live data you need to narrow it down.
Parts
Parts most often replaced for P0457: gas cap. Confirm the cause first, and match the part to your exact engine.
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Related codes
This page explains what the code usually means. It is not a diagnosis of your car. When in doubt, ask a mechanic.