Jeep Grand Cherokee P0456: EVAP System – Small Leak

The most frequent trouble code with the Jeep Grand Cherokee The Code P0456. This is the trouble code that you get when you plug in your Grand Cherokee to an internet connection. OBDII scanner. A P0456 code indicates that there may be a slight leakage in the evaporative exhaust control system. This is often seen with other codes such as P0420 or P0441.

The P0456 problem is not usually a serious threat to your Grand Cherokee'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 Grand Cherokee, it is actually referring to the amount of pressure lost, and not the physical size of the leak. This can happen in very small amounts.

Jeep Grand Cherokee Definition P0456

P0456 stands for a universal OBDII Trouble Code. The code is universal, meaning that it will be the same regardless of the make and model of your vehicle (Grand Cherokee). Technically, the code stands for:

System Leakage of Small Size – Evaporative Emission System

The EVAP captures any fuel vapor in the fuel tank, and transmits it to engines intake for ignition. When there is a small leak in the Jeep Grand Cherokee’s EVAP system, it will throw the P0456 OBDII Code. If there is a large leak, it’ll throw P0455.

Jeep Grand Cherokee OBDII Code Symptoms

A P0456 Code will not usually be associated with other noticeable symptoms. Smells like gas And the service engine soon light.

The fuel tank and fuel filler tubes should smell particularly strong.

The EVAP system is responsible for fuel vapors. 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 technology deals only with the fuel vapor. It does not impact the performance of your Grand Cherokee engine.

Grand Cherokee Trouble Code P0456

The P0456 code can be triggered by many factors in the Jeep Grand Cherokee. If your Grand Cherokee 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.

Below are the top most probable problems that could throw the code. These were listed alphabetically, in some order.

• 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. There are some clips you will need to look for and then remove.
• 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. It may be worth your time to get that message and a P0456 to ensure you don't waste any 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 Grand Cherokee

The mechanic will have a lot of different tools at his disposal in order to determine the cause of your Jeep Grand Cherokee P0456. The most commonly used methods to diagnose this code are:

• The mechanic will usually check for any additional trouble codes. A mechanic will usually check for additional trouble codes to help diagnose the problem. 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.
• Once the mechanic has determined the trouble codes associated with P0456, he or she will usually Check out the EVAP System. These include the line and purge valve.
• To ensure that the cap can withstand pressure, the mechanic will check it. 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.
• The mechanic will then perform the following tests after completing the above-mentioned checks:
• 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:

Most common P0456 fixes

These are some of the most popular Grand Cherokee P0456 solutions:

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

You should start with the gas caps and move on to the fuel tanks. This is because the gas caps are the easiest to replace and the least costly.

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

You will need to find the cause of your Jeep Grand Cherokee throwing the code P0456. This should help. Please feel free to add anything below.

Do you consider P0456 to be a serious concern?

While P0456 is not going to cause the Grand Cherokee’s engine to stop running, it should not be treated lightly. Fuel leaks could be a problem. You should pay extra attention to the level of your fuel tank and ensure that you're not leaking fuel. It is best to have it checked and/or dealt with immediately.

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