All codes
P0457Emissions System
EVAP System Leak Detected (Fuel Cap Loose/Off)
Fix P0457 EVAP fuel cap code. Learn why a loose or worn gas cap triggers this code and how to fix it fast.
What you may notice
Symptoms
- 01Check engine light on
- 02Fuel cap warning message in some vehicles
- 03Faint fuel odor
- 04Usually no drivability symptoms
Where to look first
Common causes
- 01Loose or improperly seated fuel cap
- 02Worn or cracked gas cap seal
- 03Missing fuel cap
- 04Damaged filler neck
- 05EVAP hose leak near the tank
Step by step
What to check and repair
- 01Remove and reseat the fuel cap until it clicks
- 02Inspect the cap seal for wear or damage
- 03Replace the gas cap if the seal is bad
- 04Inspect the filler neck for damage
- 05Smoke test the EVAP system if the code returns
What Does P0457 Mean?
The P0457 code specifically indicates an EVAP system leak caused by a loose, damaged, or missing fuel cap. It's one of the most driver-friendly codes because the fix is often simple.
Start With the Cap
Before anything else, remove and reinstall the fuel cap until it clicks. A cap that isn't fully seated is the most common trigger.
When It's Not the Cap
If the code returns with a properly tightened cap, the cap's seal may be worn, or the filler neck or EVAP hoses may have a leak.
How AI4Car Helps
AI4Car can confirm whether the EVAP code clears after tightening or replacing the cap, so you know if the simple fix worked.