Jeep Liberty P0456: EVAP System – Small Leak

The most frequent trouble code with the Jeep Liberty Is the Code P0456. The trouble code refers to a number you receive when your Liberty is plugged into an a OBDII scanner. A P0456 code indicates that there may be a slight leakage in the evaporative exhaust control system. It is sometimes found along with other codes such as P0441 or P0420.

Normally, P0456 does not pose a danger to your Liberty's driveability. Certainly anytime the service engine soon light is on, it’s good to deal with it as soon as possible.

While the trouble code may state that there is a “small leak” in the EVAP system of your Jeep Liberty, it is actually referring to the amount of pressure lost, and not the physical size of the leak. They can also be very minor.

Jeep Liberty P0456 Definition

The OBDII universal trouble code is P0456. It means that no matter what make or model vehicle you have, this code will still mean the exact same thing. Technically, the code stands for:

System Leakage of Small Size – Evaporative Emission System

The EVAP system collects fuel vapor from fuel tanks and then sends it to the intake to ignite the engine in normal combustion. When there is a small leak in the Jeep Liberty’s EVAP system, it will throw the P0456 OBDII Code. If there is a large leak, it’ll throw P0455.

Jeep Liberty P0456 OBDII Symptoms

The P0456 code is usually not accompanied with any other symptoms than those listed. The smell of gas The service engine soon light.

Particular attention should be paid to the fuel tank or fuel filler tube smell.

The EVAP process deals with fuel vapors directly. If these vapors are leaking from the system, you’ll often smell them faintly while operating the vehicle. But, it won’t affect the way the engine itself runs. The EVAP system is for fuel vapor and does not affect the operation of your Liberty engine.

Liberty P0456 Trouble Code Causes

P0456 can happen for many reasons in your Jeep Liberty. If your Liberty has warned you at all in the last few months that the fuel cap was off when it wasn’t, then replacing it would be a great first step.

These are some of the most frequent problems that can throw off the code. They're listed in alphabetical order, from the most likely to the least.

• Hose for Evap System– The hose that carries the fuel vapor from the fuel tank to the intake manifold can begin to leak. The P0456 error code will be generated. You should look for a hole or a tear in the code. This is the main problem that can cause the code.
• Vapor Canister Purge Valve– One of the most common causes of the P0456 code is the vapor canister purge valve. It’s really easy to replace. It is important to identify and remove a few clips.
• Fuel Tank Sending Unit– It is possible for the gasket that attaches the fuel sending unit to the gas tank to go bad. This could cause a drop in tank pressure which can throw off the code.
• Fuel Cap– A bad fuel cap can cause the code to be thrown for sure. Often, you’ll get a message informing you that the fuel cap is off even when it is on. You may not get the message but a P0456. This will save you time and money.
• Fuel Filler Neck– There is often a gasket where the fuel filler neck connects with the gas tank. The gasket may dry out especially if the vehicle is in dry conditions. When it dries out, the fuel tank can’t hold pressure anymore.

Diagnoses for Jeep Liberty - P0456

To diagnose the problem with your Jeep Liberty's P0456, a mechanic can use a variety of tools. The most commonly used methods to diagnose this code are:

• A mechanic will often check for any additional trouble codes. It is easier to diagnose problems if there are more codes. That’s because when they appear together in certain combinations, there will often only be only a few conditions that will throw any combination of codes at one time.
• The mechanic will normally determine what trouble codes are associated with P0456. Take a look at the EVAP system. It includes the purge valve and line as well as the canister.
• A mechanic will examine the gas cap and verify that it is able to withstand high pressure. If you are getting a warning that your gas cap is off, even when it’s on, replacing it will more than likely clear this code.
• Monitor and check the pressure in your fuel tank.
• Following the inspections and repairs, the mechanic will conduct two more tests.
• A smoke test, and they’ll use a scan tool to confirm that the EVAP solenoids and valves are operating properly.

Here’s a pretty good video on diagnosing these leaks from Scotty Kilmer, if you are interested:

The Most Popular P0456 Fixes

These are some of the most popular Liberty P0456 solutions:

• Replacement of gas cap
• Replacement for EVAP Line
• Replace charcoal canister
• Change the fuel tank

It is best to begin with the gas cap, and then work your way up to the fuel tanks. The gas cap is the most difficult and cost-effective item to replace.

Here’s a great video on How to check your gas cap.

You will need to find the cause of your Jeep Liberty throwing the code P0456. We trust this helped. You can add any additional information by leaving a comment.

Do you consider P0456 to be a serious concern?

While P0456 is not going to cause the Liberty’s engine to stop running, it should not be treated lightly. Fuel leaks could be a problem. Check your tank regularly to make sure there is no fuel leaking. You should immediately take it in for repair or replacement.

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