Trouble code · Powertrain · Generic (all makes)

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

The EVAP system found a large leak – most often because the fuel cap is loose, missing or not sealing.

Safe to drive?
Usually OK to drive
Get it checked soon
Scanner you need
Any OBD2 scanner
Even a basic code reader shows it
NHTSA complaints quoting it
9
Vehicle complaints, 2015–2025

Common causes

  • Loose, missing or damaged fuel cap
  • Cracked filler neck
  • Worn cap seal

Symptoms

  • Check engine light, sometimes with a 'check fuel cap' message
  • Possible fuel smell

Can I drive with it?

Safe to drive. Tighten the cap until it clicks.

Tip: Tighten or replace the cap, then drive for a few days – the light often goes out on its own after the system re-tests.

Which scanner reads it?

Any OBD2 scanner reads and clears it.

Budget tools like the ANCEL AD310 read it; tools with live data and graphing – like the BlueDriver or OBDLink MX+ – help you find the cause. Not sure which fits you? Try the Find My Scanner quiz.

In the data

Of the vehicle complaints owners filed with NHTSA from 2015 to 2025, 9 quote P0457 – most often from Ford, Mercury, Chrysler owners. Complaints lean toward serious problems, so treat this as a sign of how often the code turns up in real reports, not how often cars get it.

Both sources are compared on the Trends page.

General information to help you understand a code – not a diagnosis. Your car’s service information or a qualified mechanic has the final word. See how we research.