P0456 Code (Symptoms, Causes, Fixes & Cost 2022)

A P0456 trouble code is defined as a small evaporative emissions (EVAP) system leak. Read below to find out what does code P0456 mean, symptoms, and how this code can be fixed.

What does P0456 code mean?

Today, modern vehicles have Onboard Code Diagnostic Techniques that enable users to identify and understand the root of the issue quickly. When an issue or fault is detected in the vehicle’s emission system, the system automatically generates a diagnostic trouble code.

A P0456 code means that the Powertrain control module or engine computer has identified a small leak in the evaporative emissions system. The evaporative emissions system on a vehicle is an often-misunderstood system.

Among other reasons driving down the road causes fuel to slosh around in the fuel tank, this creates fuel vapors. The Evaporative Emissions (EVAP) system is used by the vehicle to capture and store the fuel vapors that are released.

Once the vehicle determines certain vehicle parameters have been met, the vapors are introduced into the engine and burned. This allows the vehicle to harmlessly dispose of these otherwise harmful vapors and reduce vehicle emissions.

When certain parameters have been met the vehicle does what is called a “EVAP leak test” If a leak of a certain amount is detected the PCM will set code P0456 “Small EVAP leak”

Symptoms of P0456 Codes

If the P0456 trouble code is active in your vehicle, it might be difficult to diagnose as this system is generally a system that runs in the background, unnoticed by drivers. You may not notice any issues while driving the car as the leak has no direct or indirect effect on the car’s drivability.

A few noticeable symptoms can be:

  • The check engine light is being turned on.
  • Pungent smell of gasoline.
  • A more careful observation is a decline in fuel efficiency.
  • Difficult to fill up on fuel

Common Causes for P0456

A P0456 code indicates an evaporative emission control leak. The EVAP system is designed to prevent fuel vapors from escaping into the atmosphere.

Most will tell you that the most common cause of this code is a gas cap that is loose. While it is always easy to check this a loose gas cap generally sets a Large EVAP Leak code

A few of the more common causes of this code can be:

  • EVAP hose that is disconnected/loose
  • Damaged EVAP hose
  • Leaking fuel tank (Corrosion, bad fuel pump o ring)
  • Filler Neck Corroded
  • Fault in the vent and purge control valve
  • Diagnostic Sensor Fault

How to Fix the P0456 Trouble Code?

A P0456 code can sometimes be a difficult issue to fix in your home garage. Some specialized equipment is needed to be able to properly “Smoke” test the EVAP system.

A Smoke test is a test where pressurized smoke is introduced into your EVAP system. Once the smoke travels through the EVAP system, you can search for smoke leaks indicating where the possible EVAP leak is coming from.

But before you run out to a shop to get this repaired there are a few items that can be checked quickly and easily.

Inspect the EVAP hoses under the hood and under the vehicle. Ensure that they are not damaged or possibly have come loose. While not normally the issue make sure the gas cap is on tight.

Once that is done inspect the wiring going to the components of the EVAP system. Inspect for corrosion or any other signs of damage that may be present.


Can I drive my vehicle with this code?

You do not have to worry if a P0456 trouble code is diagnosed in your vehicle. The seriousness of the trouble code is relatively low. You will not notice any issues while driving your car in most cases.

But this does not mean that you should wait until the point where you see apparent issues in the engine. It’s quite possible that the emission system does not function properly, and it should be repaired

Estimated Repair Costs

Apart from the cost linked to the diagnosis of the P0456 code, the prices covering the equipment and labor will vary but here are some of the more common costs associated with this code.

  • Purge Control Valve-$80-$180
  • Fuel Tank -$300-$600
  • Fuel filler neck-$75-$150
  • Disconnected EVAP line-$50-$100

Some other codes that are related to P0456 are, P0442, P0440, and P0445.

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