P0457 - Evaporative Emission Control System Leak Detected (Fuel Cap Loose/Off)

EVAP system indicates a loose/off fuel cap.

Code Overview

EVAP system indicates a loose/off fuel cap.

Common Causes

• Loose gas cap not tightened fully
• Damaged or hardened gas-cap seal
• Filler-neck sealing problem
• Wrong cap or poor cap fitment

Symptoms

• Check-engine light with no drivability complaint
• Possible faint fuel-vapor smell near the filler area
• Readiness monitor or emissions test failure

Diagnostic Steps

1. Re-seat and tighten the fuel cap until it clicks fully
2. Inspect the gas-cap seal and filler neck for damage or debris
3. Make sure the correct cap is installed and fits properly
4. Clear the code and confirm the EVAP monitor no longer returns the fault

Repair Difficulty

Easy

General difficulty estimate for the most common repair path.

Likely Repairs & Cost Guides

Use test results to confirm the fault before pricing the repair.

Related OBD Codes

Browse the closest code-family pages when the same fault pattern often shows up nearby.

Next Steps

Move from the code to a diagnosis path, then into repair pricing once the fault is confirmed.