P0457
Evaporative Emission System Leak Detected (fuel cap loose/off)
- Severity
- Low
- Driving
- No driving restriction
A leak was detected in the evaporative emissions system, and the module has specifically identified a loose or missing fuel filler cap as the likely cause. The EVAP system captures fuel vapour from the tank and holds it until the engine can burn it, so it needs to be sealed. A cap that is not tight is the most common way that seal is broken - and the cheapest to fix.
Possible causes
- CommonFuel filler cap loose, missing, or not clicked home
- CommonPerished or damaged seal on the fuel cap
- PossibleWrong or non-original fuel cap that does not seal properly
- PossibleDamaged filler neck the cap seals against
What you might notice
- Check engine light on, with no change in how the car drives
- Occasionally a faint fuel smell near the filler
- Failed emissions test
What to check, in order
- Remove and refit the fuel cap, tightening it until it clicks. Then clear the code and drive normally for a few days.
- Inspect the rubber seal on the cap. A hardened, cracked or flattened seal will not hold pressure even when the cap is tight.
- Check that the cap is the correct one for the vehicle - a replacement of the wrong type is a common cause.
- Look inside the filler neck for damage or debris on the sealing face.
- If the code returns with a known-good cap correctly fitted, the leak is elsewhere in the EVAP system and needs a smoke test.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Auxiliary emission controls
P0400P0401P0402P0403P0404P0405P0406P0407P0408P0409P0410P0411P0412P0413P0414P0415P0416P0417P0418P0419P0420P0421P0422P0423P0424P0425P0426P0427P0428P0429P0430P0431P0432P0433P0434P0435P0436P0437P0438P0439P0440P0441P0442P0443P0444P0445P0446P0447P0448P0449P0450P0451P0452P0453P0454P0455P0456P0457P0458P0459P0460P0461P0462P0463P0464P0465P0466P0467P0468P0469P0470P0471P0472P0473P0474P0475P0476P0477P0478P0479P0480P0481P0482P0483P0484P0485P0486P0487P0488P0489P0490P0491P0492P0493P0494P0495P0496P0497P0498P0499