Toyota Highlander P0455: EVAP System → Leak Detected (Large)

The most frequent trouble code with the Toyota Highlander Is the P0455 Code. This trouble code is related to the emissions system. The trouble code P0455 indicates that the emissions system is malfunctioning. Large leak It is part of the evaporative emission management system (EVAP). This code is often found with or related to other codes such as P0420 and P0430.

P0455: EVAP System → Leak Detected (Large)

The P0455 issue is not usually a threat to your Highlander's driveability. Certainly anytime the service engine soon light is on, it’s good to deal with it as soon as possible though.

Toyota Highlander 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 (Highlander or otherwise). The code is technically:

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 Toyota Highlander’s EVAP system, it will throw the P0455 OBDII Code.

Toyota Highlander P0455 OBDII Code 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. It is possible to notice a slight dip in fuel economy.

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.

Highlander P0455 Trouble Code Causes

P0455 code can be triggered in Toyota Highlanders by many factors. These are some of the most frequent problems that can trigger the P0455 trouble code in your Toyota Highlander:

• Hose of the Evap System– 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. You should look for a hole or a tear in the code. This is the leading cause of 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. It may be worth your time to get that message and a P0455 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. 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 Diagnosis- Toyota Highlander

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

• The mechanic will check for any additional trouble 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.
• 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:

While the trouble code may state that there is a “large leak” in the EVAP system of your Toyota Highlander, 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

These are some of the more common Highlander P0455 fix:

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

You should start with the fuel cap. This is by far the easiest to replace and the least costly of all items.

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

You will need to find the cause of your Toyota Highlander throwing the code P0455. This should help. 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 Highlander’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.