P0456 Code: Meaning, Symptoms, Causes & Fixing

The evaporative emissions control (EVAP) system is one of the major parts of the modern vehicle. It ensures the efficient performance of your vehicle engine. The powertrain control module (PCM) of your vehicle monitors the performance of the EVAP system. When your PCM detects a small fuel leakage in the EVAP system, it triggers the P0456 code. This article deeply explains the P0456 code symptoms, causes, and its fixing.

P0456 Code Definition

The P0456 code stands for “Evaporative Emissions System Small Leak Detected.”

What Does Code P0456 Mean?

The P0456 code indicates that your powertrain control module (PCM) detects a small fuel leakage in your evaporative emissions control (EVAP) system. 

P0456 code

The evaporation emissions control (EVAP) system of your car helps in stopping the fuel vapors from going into the outer atmosphere from the fuel tank or fuel system.

Modern automobiles have an integrated EVAP system to collect the typical evaporation of fuel vapors. These vapors are then collected in an EVAP canister before being returned to the engine’s intake through a purge valve and hoses.

The powertrain control module (PCM) of your vehicle controls the vent control valve. This valve permits air to enter the charcoal canister to purge the fuel vapors into the engine intake to be burned. The purge volume control valve is used to control the fuel vapors flow from the canister to the engine inlet.

To check for leaks, your PCM runs a leak test to ensure the EVAP system is functioning efficiently.

In a typical “small leak” test, your PCM first unlocks the purge valve to produce a vacuum in the system. After this, the PCM closes the vent valve and purge valve to seal the EVAP system. Because of this, a minor leaking vent valve or canister purge valve (the inside of the valve can be the source of the leak).

At last, your PCM measures the vacuum drop through a tank pressure (FTP) sensor to check the leaks. If your PCM detects a small leak, it triggers the P0456 trouble code.

Causes of the P0456 Code

  • Loose or damaged gas cap
  • Driver error
  • A leakage in the EVAP vacuum hose
  • Bad EVAP purge control valve
  • A leak in the fuel system or fuel tank
  • Bad PCM (rare)
  • Vent valve solenoid failure
  • Damaged wires to the EVAP system
  • Charcoal canister leak
  • Broken or damaged EVAP vent solenoid
  • Faulty canister vent control valve 
  • Bad fuel tank pressure sensor
  • Bad fuel pump

Symptoms of the P0456 Code

  • One of the most common symptoms of the P0456 code is the check engine light flashing
  • A reduction in the fuel economy (rare)
  • A strong odor of fuel from the engine compartment

How to diagnose the P0456 Trouble Code

To diagnose the P0456 code, you need the following codes:

  • OBD-II Scan Tool
  • Multimeter
  • Manufacturer Manual
  • EVAP Smoke Machine
  • Electrical Contact Cleaner
  • Basic Hand Tools

Follow the below-given steps to diagnose the P0456 code:

  • Use an OBD-II scanner to check all the trouble codes stored in the PCM memory.
  • Analyze the freeze data to find the root cause of the P0456 code.
  • Clear the codes and perform a test drive. If the DTC P0456 returns, perform further inspection.
  • Visually inspect the EVAP system to check for a visual leak.
  • Inspect the electrical connections and wires of the evaporative emissions control system for damage.
  • Inspect the gas cap of your fuel tank for damage or leak.
  • Inspect the gas tank for damage.
  • Inspect the EVAP vacuum hose for a leak.
  • Inspect the fuel system and fuel pump for a leak.
  • Inspect the entire vapor purge valve system for damage, including the vent valve hose and the purge valve.
  • Inspect the purge valve vent for any blockage from spider webs, dirt, or debris that may cause the valve to not be able to complete a total seal of the vapors.
  • Inspect the purge control valve to check whether it holds a vacuum or not when activated.
  • If you still are unable to find the leak, then perform a smoke test. The smoke test is the best option to find leaks and hidden issues in the system.
  • Inspect the PCM for fault.

Common diagnostic mistakes of the P0456 Code

  • Replacing the purge control valve without doing a thorough diagnostics of the complete system
  • Replacing the unnecessary parts
  • Not finding the leak and replacing the components that may or may not be the issue
  • Not clearing the memory of the powertrain control module (PCM) after fixing the issue

 P0456 Code Repair Cost

The repair or fixing cost of the P0456 code depends on your vehicle model, labor cost, and the nature of the repair. To fix the P0456 code, you need one or more of the below-given repairs: 

EVAP lines repair$20 to $110
Gas cap replacement$20 to $70
Fuel gauge sender replacement$240 to $410
Purge valve replacement$140 to $320
PCM replacement$240 to $3000

FAQ Section

What is the P0456 Jeep?

P0456 is a diagnostic trouble code. It indicates a small fuel leak in the EVAP system of your vehicle.

What repairs can fix the P0456 code?

  • Tightening the gas cap if it is loose
  • Replacing the damaged gas cap
  • Replacing or repairing the damaged or leaking fuel tank
  • Repairing the leaking EVAP vacuum hoses
  • Cleaning of the clogged purge vent valve
  • Replacing the faulty EVAP control purge valve
  • Repairing the damaged wirings to the EVAP system
  • Repairing the leaking fuel system
  • Replacing the faulty charcoal canister

How serious is the P0456 code?

The P0456 code is not a serious trouble code. This code indicates a leak in the EVAP system. You will not observe drivability issues when this code appears in your vehicle.

The only thing that could happen is the illumination of the check engine light. The existence of this code may increase the emissions of exhaust gases.

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