P0456 Code Dodge: EVAP System Leak – Causes and Fixes

Code P0456 is a generic diagnostic trouble code triggered when there is a leak in the evaporative emission control system. It has a low severity, meaning you can drive your Dodge for a short distance. But you should book an appointment with your mechanic at the first opportunity.

The DTC P0456 (Evaporative Emissions System – Small Leak Detected) has different causes, including the following:

  • Loose or damaged gas cap
  • Leaking or disconnected EVAP hose
  • Faulty purge volume control valve
  • Faulty canister vent control valve
  • Charcoal canister leak
  • Leaking fuel tank

The first signs when this code is stored in the engine control module (ECM) include decreased fuel economy and vehicle emissions. The Check Engine Light will be on, and you will smell gasoline in the cabin.

Read on for detailed information about the causes and how to fix the P0456 Dodge code.

What is Dodge P0456 Code?

By definition, the code P0456 is an OBD2 generic code set by the ECM when it detects a leak in the Evaporative Emission (EVAP) System. This code is activated when the test fails twice in a row.

p0456 DTC

An EVAP system traps fuel vapors, preventing them from increasing your vehicle’s emissions. It uses charcoal pellets to absorb fuel from the exhaust. These are then blown back into the engine for combustion through a controlled process.

The purge valve, which controls the flow of the gas vapors from the charcoal canister to the engine air intake, is closed during the EVAP test by ECM. The ECM activates the evaporative vacuum pump and monitors the system for leaks. If it detects a small leak, the P0456 code is stored, and the Check Engine Light comes on.

What Causes Code P0456?

EVAP is a complex system consisting of a Fuel Tank, Gas Cap, Liquid-Vapor Separator, Purge Valve/Sensor, EVAP Canister, Vent Control Valve, and Vent Hoses. A fault in these components will cause the ECM to store the P0456 code. Let’s break it down to better understand the causes of code P0456 Dodge.

Loose Or Damaged Gas Cap

A gas cap should seal the EVAP system. A loose or damaged one will not perform that duty, and regulating pressure within the fuel tank becomes a problem. During the EVAP test, the loosely fitted or damaged cap will cause leaks, which makes the ECM store the P0456 code.

Loose Or Damaged fuel Cap

You can fix this problem by tightening your gas cap. But if it is damaged, you may need to buy a replacement.

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Leaking Or Disconnected EVAP Hose

EVAP hoses or vent lines run from the fuel tank to the vapor canisters. They are the channels that prevent fuel vapor from escaping to the atmosphere. Instead, they are directed to the vapor canister, where they are absorbed and stored with the help of charcoal pellets.

Leaking or disconnected hoses allow fuel vapor to evaporate into the atmosphere. During the vacuum test performed by the ECM, small leaks are detected, and code P0456 is stored in the system.

Faulty Purge Volume Control Valve

A purge volume control valve is a vital component of an EVAP system. It allows the ECM to control the number of fuel vapors that flow back to the engine manifold intake from the canister. This component is electronically operated by the engine’s computer in modern vehicle models.

A faulty canister purge valve fails to perform its functions. It may fail to open or close as commanded by the ECU, making the fuel vapor control impossible. The ECM detects this during the EVAP system test and triggers the code P0456.

Faulty Canister Vent Control Valve

A canister vent control valve or vent valve does just what its name suggests. This component controls the amount of air that flows in and out of the EVAP system. That air helps to blow fuel vapor absorbed in the charcoal pellets inside the canister back to the engine manifold for combustion.

A faulty vent valve will not close as it should. It will have leaks, which cause ECM to store the code P0456 and turn on the Check Engine Light.  

Charcoal Canister Leak

A charcoal-filled canister is the heart of an EVAP system. Its function is to absorb the fuel vapors that would otherwise escape into the atmosphere. These trapped vapors are then released into the engine’s intake manifold through a controlled process.

Charcoal Canister

Like all other EVAP system components, the charcoal canister has to be airtight. A leak on it will trigger the P0456 code when ECM tests the system.

Other symptoms of a failing charcoal canister include the following:

  • High rate of emissions
  • Poor fuel economy
  • Pinging sounds from the engine
  • Fuel odor in the cabin
  • Reduced engine performance
  • Trouble starting the engine
  • Leaking Fuel Tank

All EVAP system components have to remain airtight, including the fuel tank. Any leaks here will make the system fail the test, making ECM store the P0456 code. As part of the diagnosis, you should also check the fuel tank and ensure there are no leaks.

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Symptoms of Dodge P0456 Code

It may only be possible to notice this problem if you are keen. Otherwise, you may only realize something different apart from the Check Engine Light that turns on. Drivers can continue driving for many miles with this code. Besides, it is a low-risk fault, and it is safe to drive your car.

The following are some of the most commonly reported symptoms of code P0456 Dodge:

  • Check Engine Light comes on
  • Slight gasoline smell in the cabin
  • Reduced fuel economy – lower mileage per gallon
  • Reduced engine performance
  • Increased vehicle emissions

How Do I Fix Code P0456 Dodge?

Small leaks in the EVAP system cause the Dodge Code P0456. These may not be visible to the naked eye, which means visual inspection may not apply.

You should diagnose your car to find the cause of Dodge Code P0456, commonly done with an OBD scanning tool.

mechanic using obd2 scanning tool

What do you need to diagnose Dodge Code P0456 effectively? The recommended tools include the following:

  • Diagnostic OBD Scan Tool
  • Multimeter
  • Basic Hand Tools
  • EVAP Smoke Machine
  • Auto Repair Manual
  • Electrical Contact Cleaner

With everything ready, you can proceed with the diagnosis as follows:

  1. Connect the OBD2 scanning tool to read the P0456 and other related codes. Some scanning tools have code definitions to help you understand the stored DTCs. But if yours does not have the DTC lookup library, find the information on the internet.
  2. Visual inspection may not apply to leaks in the EVAP system. Nevertheless, check every component. You might catch a broken or disconnected vent line.
  3. Connect an EVAP smoke machine to the EVAP system and look for leaks on the vacuum hoses and gas tank. The smoke should make the leaks possible.
  4. Disconnect the EVAP purge valve plug and perform an output test from the ECU to the EVAP with the OBD2 tool. Use a multimeter to measure the voltage across the connector plug positive terminal and ground. The voltage reading should be more than 12V for a properly functioning purge valve plug.
  5. Send 12V or more to the purge control valve plug to test if it is closing and opening the air passage. Replace it if it is unresponsive to voltage injections.

Fixing the Dodge Code P0456 involves finding faults and repairing or replacing faulty components. You can seal leaks on the fuel tank, charcoal canister, and EVAP hoses. You can also tighten the gas cap or replace it if damaged. Also, it may require you to repair or replace faulty control purge and vent valves.

Sometimes the Dodge Code P0456 is due to faulty electrical wiring to the EVAP control purge valve. You should check and fix the wires, ensuring the circuit has no shorts or opens.

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How Much Does It Cost to Fix Dodge Code P0456?

The cost of fixing the Dodge Code P0456 varies, depending on the component you need to repair or replace. Refer to the chart below for an estimate of the budget for fixing this problem.

ComponentRepair/Replacement Cost
Gas cap$20-$60
EVAP Purge Volume Control Valve$150-$200
Charcoal Canister Vent Control Valve$150-$200
Replacement EVAP Line$50-$100
Charcoal Canister$200-$600

Also, you should add the labor fees if you take your vehicle to an auto repair shop or mechanic. The diagnosis is typically charged at about $75-$150 and often includes the repair cost. However, it depends on your region.

Can I Drive with A P0456 Code?

The Dodge Code P0456 is a low-risk DTC, meaning you might still be able to drive your truck for short distances. You will not have any drivability or handling issues with your Dodge, but you may notice a reduced engine performance. But, of course, you will see the Check Engine Light on the dashboard. Although this code is not severe, you should fix it when you get the first chance. It will help you get a better fuel economy and reduce emissions.

Fortunately, you can diagnose and fix the Dodge Code P0456 yourself if you are an advanced DIYer. But you can also contact your mechanic if you don’t have the recommended tools for finding the fault and repairing it.