P0457Generic code

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

The P0457 code means the computer detected a leak in the fuel vapor system that matches a fuel cap that is loose or missing. It is the easiest EVAP code to solve. It is a low severity code and you can keep driving, but you should fix it to pass an emissions inspection.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$0 to $30
Difficulty
Easy
System
Emissions Control
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0457 code means

After you fuel up, the computer checks the EVAP system. If it finds a large leak right after a fill-up, it assumes the cap was not closed properly and stores the P0457 code. Many vehicles also turn on a loose cap warning on the dashboard.

Tighten the cap until it clicks and drive for a few days. The check engine light goes out by itself once the EVAP monitor finishes without finding a leak. If it comes back, check the cap gasket and the filler neck.

See the P0455 code entry if the problem returns even though the cap is closed correctly.

If the vehicle has no cap at all (a capless system), the code is usually caused by the inner flap in the filler neck not closing well, often because of dirt. Clean the area and check that the flap returns to its closed position. On vehicles that do have a cap, always use an original or an equivalent quality part: cheap generic caps are a frequent reason for repeated P0455 and P0457 codes.

P0457 code symptoms

  • Check engine light on after fueling.
  • Loose cap warning on the dashboard (some vehicles).
  • Gasoline smell near the fuel cap.

Likely causes of the P0457 code

  1. Cap loose or left off. This is the usual cause.
  2. Cracked cap gasket. The cap closes but does not seal.
  3. Non-original cap that does not seal.
  4. Rusted filler neck. Rust opens tiny pores under the body.

How to diagnose the P0457 code step by step

  1. Check the cap and its gasket. Look for cracks, hardening or missing pieces.
  2. Tighten it until it clicks.
  3. Clear the code and drive for several days to give the EVAP monitor time to run.
  4. If it returns, do a smoke test. That is how you find the leak.
  5. On vehicles without a cap, clean the flap in the filler neck and check that it closes.

How to fix the P0457 code

  • Tighten the cap, or replace it with an original one.
  • Replace the filler neck if it is rusted.
  • Clear the code.

Technical reference data

  • The EVAP monitor can take several days to run.
  • Reference values: check the manufacturer data for your engine.

Brand-specific notes

The P0457 code is mostly about the cap, whatever the make. Capless systems are the exception, and they need a different check.

P0457 on Ford

On Ford and other vehicles without a cap (the Easy Fuel system), check that the inner flap closes properly.

Frequently asked questions about P0457

What does the P0457 code mean?
It means the computer found an EVAP leak that fits a fuel cap that is loose or missing. The check usually happens right after a fill-up.
Is the P0457 code serious?
No, but you should fix it so the vehicle can pass an emissions inspection. It does not affect how the engine runs.
How long does the light take to go out?
Usually one to several days of driving. The light goes out once the EVAP monitor finishes a full test without finding a leak.
Can I drive with a P0457 code?
Yes. It is safe to drive, although some fuel vapor may be escaping, so tighten the cap as soon as you can.
How much does it cost to fix P0457?
It costs $0 to $30 if the cap is the problem. Tightening it is free, and a new original cap is cheap.
Will a P0457 code clear itself?
Yes, in most cases. Once the cap is tight, the light turns off by itself after the EVAP monitor runs again without finding a leak.
What is the most common cause of P0457?
A fuel cap that is loose or was left off after fueling. After that, a cracked cap gasket or a cheap non-original cap that does not seal is the usual finding.

Related codes

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