P0456 Code (Symptoms, Causes, and Fixes)

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Modern cars are built with an onboard central computer that can detect and report virtually any fault or damage on the built-in systems and components. To get information from your car’s onboard computer, you need an OBD-II scanner and also learn about DTCs – Diagnostic Trouble Codes.

P0456 code is a DTC – Diagnostic Trouble Code – that’d pop up in your auto troubleshooting device (e.g. OBDII Scanner) if your car’s computer detects a leak within the EVAP system.

If you’ve got an illuminated check engine light, and have been experiencing several unusual signs while driving, which led you to troubleshoot your vehicle to get the P0456 code, this article explains every possible solution you need to navigate the situation.

What Does The P0456 Code Stand For?

This DTC means – “Evaporative Emission System – Small Leak.”

P0456 error code simply signifies that there’s a small leak in the EVAP system of your vehicle. The EVAP system is the Evaporative Emissions System, which is in charge of controlling and preventing fuel/gas vapor from escaping the fuel cap into the atmosphere.

Any damage to the components that make up the EVAP system would contribute to a drastic decrease in your car’s fuel economy, and also pose a potential fire hazard. Hence, the car’s central computer is designed to also check this system for leaks and faultiness.

The EVAP system in modern vehicles comprises hoses, valves, a charcoal canister, and a fuel cap. When any of these EVAP system components goes bad, you’d most likely notice any of these symptoms.

What Causes the P0456 Code to Appear?

What Causes the P0456 Code to Appear

The components that make up the EVAP system are subject to physical damage and excessive wear due to their positions; hence, they have higher possibilities of going bad from time to time.

Once there is a “small” leak in the EVAP system, this code would appear on your OBD-II device when you scan the affected vehicle. Below are the causes of the P0456 DTC.

  • Broken or malfunctioning purge vent valve
  • Cracked or missing fuel cap
  • Leaky EVAP hose
  • Leaks in the fuel tank
  • Faulty canister valve
  • Damaged charcoal canister

Symptoms of P0456 DTC

  • Fuel Finishes Faster: When you notice that your car seems to utilize more fuel than it ever does, it could be that the fuel cap is cracked or not tightened.
  • Check Engine Light is On: Although there are several issues that can trigger the check engine icon to illuminate, a faulty EVAP system component can also do that.
  • Gaseous Smell: Since the EVAP system compresses fuel vapor – prevent it from escaping – a crack in the system would cause the vapors to escape; hence, you’d always perceive gaseous smell while in, or around your car.

Is This a Serious Issue?

No. Not really. The P0456 code means that the leak detected in the EVAP system is small. If the leak is a serious one, you’d rather be presented with P0457 or P0455 DTC.

So, since the detected leak is not too severe, the situation is not such to make your mind skip beats. Notwithstanding, you need to fix and replace the leaky component as fast as possible to prevent the issue from escalating.

How To Fix P0456 Error Code

You can fix the P0456 error code by yourself; but if it happens you need to replace a leaky valve or host, it is best to engage a mechanic. Below are the DIY steps to fixing this DTC.

1. Scan for Other Codes

Connect your OBD-II scanner and check if other error codes would come up. If there are no other DTCs except the P0456 code, proceed with the subsequent steps below.

2. Check The Purge Valve and Hoses

Physically inspect the vapor purge valve, hoses, and connectors for leaks. If any of these is physically damaged, you’d need to get it replaced.  Also, check to see if the hoses are clogged or blocked – so you’d have to unclog them to fix the issue

3. Inspect the Entire EVAP System

Of course, since you’re already getting an error code that’s related to the EVAP system, it is important to check all the components that make up this system, which includes the fuel cap, vacuum hose, lines, and charcoal canister. Any damaged one would need a replacement for the P0456 error to disappear.

4. Clear the Code

When you’re done unclogging and replacing the faulty component that caused the code to appear, clear the code from the system using the OBD-II scanner. Once this is done, you’re good to go.

It costs around $200 – $300 to fix the P0456 error. The cost is majorly the amount paid to buy the replaced faulty components and the diagnostics fee charged by the mechanic.

What More?

The P0456 code indicates there’s a minor leak in your car’s EVAP system. It is not a severe issue, but still, you should act fast to fix the faulty component causing the leak.

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