P0457 Code Symptoms and Causes (and Repair Cost 2022)

The evaporative emission system is designed to keep fuel vapor from leaking out into the surrounding air and causing pollution. If there’s a vacuum leak in this system, a P0455P0453, or P0457 code will be detected and stored by the PCM. Diagnostic trouble code P0457 is largely indicative of a significant vacuum leak within a vehicle’s evaporative emissions system. This article explains the P0457 code symptoms and causes. 

P0457 Code Definition

Diagnostic trouble code (DTC) P0457 stands for “Evaporative Emission System Leak Detected (Fuel Cap Loose/Off).”

What does P0457 Code Mean?

The P0457 code indicates that your powertrain control module (PCM) detects a large leak in the evaporative emission control system.

P0457 code

In the majority of cases, this code simply indicates that a vehicle’s gas cap has been left loose or is missing entirely. However, this same code can also be indicative of other leaks within a vehicle’s evaporative emissions system.

To understand the root cause of DTC P0457, one must first understand the nuances associated with the evaporative emissions control system.

The evaporative emission control system is designed to recirculate unburnt exhaust vapors into an engine’s intake manifold where they are burnt in their entirety, thereby reducing a vehicle’s carbon footprint.

A vehicle’s evaporative emissions system operates on the vacuum principle to prevent fuel from evaporating into the atmosphere. However, this safeguard is significantly compromised when a leak of one type or another presents itself, as is indicated by the logging of diagnostic trouble code P0457.

EVAP System Function

The evaporative emission control system (EVAP) keeps fuel vapor from escaping into the atmosphere.

A typical EVAP system controls the following primary components:

  • The fuel tank
  • Hoses and lines that connect the system together
  • A vent valve that closes during system testing
  • The gas cap
  • A purge valve
  • A pressure sensor that measures the pressure in the fuel tank
  • A charcoal canister that captures the fuel vapor

The focal point of the EVAP system is the charcoal canister—a component that stores the fuel vapors when the engine is off.

When the engine is running, and conditions are correct, the PCM opens a device called the purge valve. This allows the vapors to be drawn into the engine, where they are burned as part of the normal combustion process.

Many vehicles can check whether refueling has taken place by monitoring parameters, such as the ignition switch and fuel level. If the PCM detects an EVAP system leak shortly after refueling, it assumes the gas cap was left loose and sets code P0457.

The code can also be triggered by a large leak somewhere else in the EVAP system.

Causes of the P0457 Code

In most cases, a P0457 code is stored due to:

  • Loose, cracked, or damaged gas cap
  • Leaking fuel tank
  • Charcoal canister leak
  • Leaking or disconnected EVAP hose
  • A cracked vacuum canister
  • Faulty purge volume control valve
  • Damaged fuel filler neck

Symptoms of Code P0457

In the vast majority of instances, diagnostic trouble code P0457 is not accompanied by any underlying drivability issues. Following are the most common symptoms of the P0457 code:

  • Poor fuel economy
  • Fuel smell
  • Illuminated check engine light

How to Fix P0457 Code

Follow the below-given steps to diagnose or fix the P0457 code:

1) Check for the Presence of other Codes

Because the P0457 code doesn’t generally present any symptoms other than an illuminated Check Engine Light, it’s necessary to use an OBD-II scanner to detect what kind of code is causing the light to turn on. 

2) Inspect Gas Cap

Once the P0457 code is identified, visually inspect the gas cap. Look for signs of damage or wear while also ensuring that your gas cap is fully tightened to the point of “clicking.”

3) Clear Code/Test Drive

With your gas cap firmly in place, you will now clear the offending P0457 trouble code using a scan tool. With this code cleared, take your vehicle for a reasonable test drive, ensuring that no your check engine light does not return.

4) Visually Inspect EVAP System

If your vehicle’s check engine light returns, a careful visual inspection of the vehicle’s EVAP system is in-store. Check for signs of distorted or damaged EVAP lines while also verifying the structural integrity of the vehicle’s charcoal canister.

Replace any such items that are found to be defective.

5) Test for Leaks

It will now be necessary to check for any leaks that might be present. This can be done in one of two ways.

A smoke tester can be hooked inline at the EVAP hose’s intake manifold junction. Within seconds, smoke should begin billowing from the offending leak.

FAQ Section

Is Code P0457 Serious?

The P0457 code is the most severe code related to leaks in the evaporative emission control system. It can increase your vehicle’s fuel emissions while decreasing your fuel economy. Depending on the problem, it could lead to even larger fuel leaks, which could be more expensive and cripple your vehicle until you resolve them.

How much does it cost to fix Code P0457?

The repair cost of the P0457 code depends on the vehicle model and the labor cost. The average repair cost of the P0457 code is from $70 to $160.

What repairs can fix the P0457 code?

The most common repair for this code is to either ensure that the gas cap is tightened properly or to replace it. Other repairs include:

  • Replacing one or more of the evaporative emission control system’s vacuum hoses.
  • Replacing the charcoal canister if it shows signs of cracks.
  • Ensuring that the intake manifold’s fitting is sealed and free of cracks and replacing it if needed.
  • Inspect the gas cap and replace it if needed.

What is the code for a faulty gas cap?

A P0457 gross leak detected code is often the result of the vehicle’s operator not tightening the refueling cap correctly after refueling. The same is true for the P0455 large leak fault code. A loose gas cap is not the only possible cause, but it’s undoubtedly the most likely.

How many times should you click a gas cap?

Many manufacturers recommend tightening the fuel cap until it clicks three times, which is just a random number to make sure the cap is tight.

Will the check engine light go off after tightening the gas cap?

The check engine light should go off after you drive for several minutes if a loose gas cap causes the light. Pay attention to the dashboard after the check engine light experience. If you find that the light keeps coming on, and goes off again once you tighten the gas cap, then your gas cap is too loose.

What happens if you over-tighten the gas cap?

You shouldn’t overtight your gas cap. Listen for one click and stop; otherwise, you can damage the seal, and your check engine light may come on. Never buy aftermarket or locking gas caps. They do not seal most of the time properly and may cause your check engine light to come on.

Should all gas caps click?

The gasket and the pressure relief valves are the only two components on the gas cap itself that will cause it to not “click” or tighten as it should.

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