Parts
$0–25
P0457 — EVAP System Leak Detected — Fuel Cap Loose/Off
SAFEIs it safe to drive? Tighten your gas cap and drive a few normal cycles — if the light clears, you're done; if it doesn't, there may be a real EVAP leak.
What P0457 means
The ECM's EVAP leak test detected a large pressure loss consistent with an unsecured fuel cap. Some vehicles set this specific code (vs. P0455) only when the cap is confirmed loose or missing. It's the cheapest code to fix: tighten the cap until it clicks.
Most likely causes (in order)
- Gas cap not fully tightened after fill-up
- Gas cap seal cracked or hardened (a $10–20 cap)
- Incorrect cap installed (wrong part number — EVAP pressure rating matters)
- Fuel neck or cap sealing surface damaged
- Actual large EVAP leak elsewhere (if cap checks out OK)
Symptoms you might notice
- fuel smell near tank
- CEL on
- no driveability impact
What to check first
Tighten the cap until you hear clicks, drive two complete warm-up cycles, and see if the light self-clears. If it doesn't clear within a week of normal driving, buy a new OEM-spec cap ($10–20) — aftermarket caps frequently don't seal correctly on modern tight-tolerance EVAP systems.
Repair cost & difficulty
Labor
0.1 hr
Difficulty
Easy DIY