Chevy Silverado P0455: EVAP System Large Leak Detected Diagnosis

The most frequent trouble code with the Chevy Silverado The Code P0455. The trouble code refers to a number you receive when your Silverado is plugged into an OBDII scanner. The trouble code P0455 indicates that there are a Large leak In the evaporative emissions control system. It is frequently found in conjunction with other codes such as P0420 or P0441.

P0455: System Gross Leak Evaporative Emission

Your Silverado’s driveability 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 may also be accompanied with P0442. See Chevy Silverado P0442 OBDII Code for more.

Chevy Silverado P0455 Definition

P0455 refers to a general OBDII trouble code. The code is universal, meaning that it will be the same regardless of the make and model of your vehicle (Silverado). Technically, the code stands for:

System Gross Leak Evaporative Emission System

The EVAP captures any fuel vapor in the tank, and then transmits them to engines intake for ignition. When there is a large leak in the Chevy Silverado’s EVAP system, it will throw the P0455 OBDII Code.

Chevy Silverado P0455 OBDII Code Symptoms

The P0455 code is usually not accompanied with any other symptoms than those listed. The smell of gas The service engine soon light. The slightest drop in fuel economy may also be noticeable.

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.

Silverado P0455 Trouble Code Causes

You can have the Chevy Silverado's P0455 trouble code trigger for many reasons. The most frequent problems that trigger this code are:

• Evap 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. 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 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.
• A Faulty Canister of Charcoal– 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. It can lower the tank pressure, which could throw out 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. It is possible for this gasket to dry, particularly if vehicles spend a lot of time in dry environments. When it dries out, the fuel tank can’t hold pressure anymore.

P0455 Diagnostics- Chevy Silverado

To diagnose the problem with your Chevy Silverado's P0455, a mechanic can use a variety of tools. The most commonly used methods to diagnose this code are:

• A mechanic will often check for additional 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 P0455, he or she will usually Check out the EVAP System. It includes the purge valve and line as well as the canister.
• 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.
• Monitoring and checking the fuel tank pressure is a must.
• 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:

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

Most common P0455 fixes

Below are the most commonly used Silverado P0455 solutions:

• Replacing the gas cap
• Replacing EVAP lines
• Replace charcoal canister
• Replacing 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 test your gas tank.

We wish you all the best in finding out why your Chevy Silverado is throwing the P0455 code. We trust this helped. You can add any additional information by leaving a comment.

Are P0455 Serious Concerns?

While P0455 is not going to cause the Silverado’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.