Jeep Grand Cherokee P0456 Code: What It Is And How To Fix It

Today’s vehicles use what’s called an Evaporative Emission Control (EVAP) system to prevent harmful hydrocarbons from entering the atmosphere. This system collects and stores gasoline fuel vapor to burn rather than releasing it into the atmosphere. Many Jeep Grand Cherokee owners have reported the P0456 error code, described as an Evaporative Emission Control (EVAP) System Leak Detected (Very Small Leak). We’ll cover everything you need to know about this troublesome fault code in this article.

What Does The P0456 Error Code Mean?

The P0456 error code indicates your EVAP system is leaking fuel vapor. The code further designates the leak as very small. The EVAP system is a self-monitored emissions system device designed to reduce the release of hydrocarbons into the atmosphere. When the EVAP system fails a self-test, the corresponding error code is set by the Powertrain Control Module (PCM), and the check engine light is illuminated. In the case of the P0456 error code, the EVAP system self-test failed by detecting a very small fuel vapor leak.

What Causes The P0456 Error Code?

The most common cause for the P0456 code is a fuel vapor leak. Vapor leaks can be both external, releasing vapor to the atmosphere, and internal, when the vapor escapes storage or is prematurely burned.

The following are the possible causes of the P0456 error code:

• EVAP system plumbing leak
• Leaking charcoal canister
• Leaking fuel tank or fuel pump seal
• Faulty Evaporative System Integrity Module (ESIM) switch or wiring issue
• ESIM mounting seal leaking
• ESIM internal check valves leaking
• ESIM mounted incorrectly on the canister
• Purge solenoid leaking
• Restriction in the canister

The ESIM is also referred to as the leak detection pump. Below, we can see a defective ESIM.

Symptoms Of The P0456 Error Code

The illuminated check engine light is the most prevalent symptom of the P0456 error code. Other Grand Cherokee owners have reported the following symptoms:

• Fuel odor
• Decreased fuel efficiency
• Emission test failure
• Illuminated “check fuel cap” light

Can I Drive My Jeep Grand Cherokee With This Issue?

Your Grand Cherokee will fail emissions testing while the fault is present. Additionally, the EVAP system will not be operating properly so your vehicle will be releasing hydrocarbons into the atmosphere. Because the error code only causes minor drivability issues, you may continue to drive your Grand Cherokee while the fault is present. However, we recommend getting it fixed soon since the fault releases harmful vapors that contribute to smog formation.

How To Fix A P0456 Error Code On Your Vehicle

There are several possible fixes for a P0456 error code on a Jeep Grand Cherokee. The most common repair is the replacement of the leak detection pump or ESIM, but we’ll cover a few other culprits as well.

Before replacing any parts, you’ll want to have your vehicle’s computer scanned to verify the P0456 error code is active. Once you’ve verified the code, it’s time to perform some simple checks.

EVAP System Visual Inspection

Fuel vapor can easily escape through the smallest cracks from hoses or the fuel filler cap. Begin by inspecting the hoses connecting the purge solenoid to the intake. If the hose condition and connections are intact, inspect the fuel filler cap. If the fuel cap seal is cracked or damaged, replace the cap immediately.

ESIM Replacement

The ESIM is a common failure point of the EVAP system for many Grand Cherokee owners. The ESIM is responsible for closing off the fresh air vent of the EVAP system during the self-test. If the ESIM fails to operate or leaks, the self-test will indicate a leak is detected. The ESIM is located on the charcoal canister and is fairly easy to remove. If the ESIM is removed and gently shaken, a rattling sound may be heard. If your ESIM rattles, replace it.

Below, we can see an ESIM from a Jeep Grand Cherokee.

Purge Solenoid Replacement

The purge solenoid allows the engine vacuum to draw in the stored vapor from the canister into the engine to be burned. If the purge valve sticks open, the self-test will indicate a leak. In most scenarios, this will result in a rich-running engine as well.

How Much Does It Cost To Fix?

There’s some variance to what you can expect to pay to fix the P0456 error code on your Grand Cherokee based on what the fault is. The cost to replace a fuel cap on your Grand Cherokee will come in around $15 – $35 and can easily be done without visiting a shop. It’s worth noting that not all Grand Cherokees have a fuel cap, though. EVAP hoses and leaks vary in cost due to parts and labor charges. If the charcoal canister is the faulty component on your Grand Cherokee, RepairPal estimates cost between $388 and $450.

A purge solenoid replacement will cost you around $100 – $150 if performed by a shop. You can save yourself here as it doesn’t require any special tools to replace it yourself. Finally, the ESIM replacement can cost between $150 and $350 if it’s done by a shop. This is another job you could perform yourself if you’re competent with basic tools.

Component Cost Estimates