Chevy Monte Carlo P0455: EVAP System Large Leak Detected Diagnosis

This is one of the most commonly encountered trouble codes for the Chevy Monte Carlo The Code P0455. This code is used to refer to the number given when you connect your Monte Carlo to an OBDII scanner. If there's a problem, P0455 means that it is. 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

P0455 does not normally pose a danger to your Monte Carlo's driveability. 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. For more information, see Chevy Monte Carlo OBDII code P0442.

Chevy Monte Carlo P0455 Definition

The universal OBDII code P0455 can be used to diagnose trouble codes. It means that no matter what make or model vehicle you have, this code can be used to indicate the same thing. 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 intake of the engine to start the combustion process. When there is a large leak in the Chevy Monte Carlo’s EVAP system, it will throw the P0455 OBDII Code.

Chevy Monte Carlo 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. It is possible to notice a slight dip in fuel economy.

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.

Monte Carlo P0455 Trouble Code Causes

Many things can trigger the P0455 code in Chevy Monte Carlo. The most frequent problems that trigger this code are:

• Evap System Hose– The hose that carries the fuel vapor from the fuel tank to the intake manifold can begin to leak. The P0455 error code will be generated. It should be checked for tears or holes. 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 Monte Carlo

The mechanic will have a lot of different tools at his disposal in order to determine the cause of your Chevy Monte Carlo P0455. The most commonly used methods to diagnose this code are:

• The mechanic will check to make sure there are no other 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.
• The mechanic will normally determine what trouble codes are associated with P0455. 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.
• 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 Monte Carlo, the actual leak will most likely still look rather small. The “large” really is referring to how much pressure is being lost.

P0455 is the most common fix

These are some of the more common Monte Carlo 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 test your gas tank.

It's a good idea to try and figure out why your Chevy Monte Carlo ejects the P0455 Code. We trust this helped. You can add any additional information by leaving a comment.

Do you consider P0455 to be a serious concern?

While P0455 is not going to cause the Monte Carlo’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. You should immediately take it in for repair or replacement.