GMC Yukon P0455: EVAP System Large Leak Detected Diagnosis

This is one of the most commonly encountered trouble codes for the GMC Yukon Is the Code P0455. This code is used to refer to the number given when you connect your Yukon to an OBDII scanner. The trouble code P0455 indicates that there are a Leakage large It is part of the evaporative emission controller system. It is frequently found in conjunction with other codes such as P0420 or P0441.

P0455: System Gross Leak Evaporative Emission

Your Yukon's drive-ability is generally not affected by P0455. Certainly anytime the service engine soon light is on, it’s good to deal with it as soon as possible though. It's often associated with P0442. For more information, see GMC Yukon OBDII code P0442.

GMC Yukon Definition P0455

The universal OBDII code P0455 can be used to diagnose any problem. The code can be used regardless of the make and model of the vehicle. Technically, the code stands for:

System Gross Leak Evaporative Emission System

The EVAP captures any fuel vapor in the fuel tank. They are then sent to the engines intake for ignition. When there is a large leak in the GMC Yukon’s EVAP system, it will throw the P0455 OBDII Code.

GMC Yukon P0455 OBDII Symptoms

A P0455 Code will usually not cause any symptoms except the ones listed below. The smell of gas And the service engine soon light. The slightest drop in fuel economy may also be noticeable.

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

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.

Yukon P0455 Trouble Code Reasons

You can have the P0455 Trouble Code trigger in your GMC Yukon for many reasons. These are some of the more common issues that can trigger the code.

• Evap System Hose– The hose that carries the fuel vapor from the fuel tank to the intake manifold can begin to leak. This can lead to the P0455 code. It should be checked for tears or holes. This is one of most frequent causes for the code.
• Vapor Canister Purge Valve– One of the most common causes of the P0455 code is the vapor canister purge valve. It’s really easy to replace. You will need to locate and take out a few clips.
• The Faulty Charcoal Caister– The charcoal canister is often the cause of P0455.
• 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 P0455. 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.

P0455 Diagnoses- GMC Yukon

To diagnose the problem with your GMC Yukon's P0455, a mechanic can use a variety of tools. These are some of the common diagnostics that can be done for the code

• Most mechanics will check for additional 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.
• Once the mechanic has determined the trouble codes associated with P0455, he or she will usually Take a look at the EVAP system. These include the line and purge valve.
• 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:

While the trouble code may state that there is a “large leak” in the EVAP system of your GMC Yukon, the actual leak will most likely still look rather small. The “large” really is referring to how much pressure is being lost.

The Most Popular P0455 Fixes

Below are the most commonly used Yukon P0455 fix:

• Replacing the gas cap
• Replacement for EVAP Line
• Replace charcoal canister
• Change 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 GMC Yukon throwing the P0455 code. We trust this helped. Please feel free to add anything below.

Are P0455 Serious Concerns?

While P0455 is not going to cause the Yukon’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. It is best to have it checked and/or dealt with immediately.