P0457
EVAP System Leak Detected (fuel cap loose/off)
Evaporative emissions (EVAP)
Generic OBD-II
Low
What it means
P0457 means the evaporative emission system detected a leak that it traced to a loose or missing fuel cap — vapors that should stay sealed in the tank and charcoal canister are escaping. Nine times out of ten it's simply a cap that wasn't tightened or has a worn seal. The car drives fine; the concern is emissions and fuel-vapor loss.
Low
Can I keep driving? Yes — the car drives normally; this is an emissions and fuel-vapor issue, not a mechanical one.
Common symptoms
What you'll notice
- Check-engine light on
- Occasional smell of fuel vapor near the vehicle
- Failed emissions test
Common causes
Most likely first
- Loose, missing, or worn fuel cap (by far the most common cause)Likely
- Cracked or damaged fuel filler neck or cap sealCommon
- Loose or damaged EVAP hose near the tankCommon
- Faulty fuel tank pressure sensorLess often
How to diagnose & fix
Work through it in order
- Remove and reseat the fuel cap firmly until it clicks; replace it if the seal is worn or cracked.
- Drive several complete cycles so the monitor can re-run, then see if the code clears.
- Inspect the filler neck and cap seal for cracks or debris.
- Check the EVAP hoses near the tank for looseness or damage.
- If it persists, have the EVAP system smoke-tested to pinpoint the leak. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0457?+
Yes. It only affects fuel-vapor containment and emissions — nothing that impairs how the car drives.
Can I just clear P0457?+
Tighten or replace the cap first, then clear it. If the cap wasn't the problem it will return until the actual leak is fixed.
Related codes
Often seen with P0457
Read & clear P0457 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX