Toyota Sequoia P0456: EVAP System – Small Leak

This is one of the most commonly encountered trouble codes for the Toyota Sequoia Is the Code P0456. The trouble code refers to a number you receive when your Sequoia is plugged into an a OBDII scanner. A P0456 code indicates that there may be a slight leakage in the evaporative exhaust control system. This code is often found with or related to P0420,P0441 and, very rarely, P0440.

The P0456 issue is not usually a threat to your Sequoia's driveability. Certainly anytime the service engine soon light is on, it’s good to deal with it as soon as possible.

While the trouble code may state that there is a “small leak” in the EVAP system of your Toyota Sequoia, it is actually referring to the amount of pressure lost, and not the physical size of the leak. This can happen in very small amounts.

Toyota Sequoia P0456 Description

The universal OBDII code P0456 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 Leakage of Small Size – Evaporative Emission System

The EVAP captures any fuel vapor in the fuel tank, and transmits them to engines intake for ignition. When there is a small leak in the Toyota Sequoia’s EVAP system, it will throw the P0456 OBDII Code. If there is a large leak, it’ll throw P0455.

Toyota Sequoia P0456 OBDII code Symptoms

A P0456 Code will not usually be associated with other noticeable symptoms. Smells like gas The service engine soon light.

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. But, it won’t affect the way the engine itself runs. Your Sequoia's engine will not be affected by the EVAP system.

Problem Code Sequoia P0456

P0456 Trouble code can occur for many reasons in your Toyota Sequoia. If your Sequoia has warned you at all in the last few months that the fuel cap was off when it wasn’t, then replacing it would be a great first step.

These are some of the most frequent problems that can throw off the code. They're listed in alphabetical order, from the most likely to the least.

• Evap System Hose– The hose that carries the fuel vapor from the fuel tank to the intake manifold can begin to leak. The code P0456 will occur. 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 P0456 code is the vapor canister purge valve. It’s really easy to replace. You'll need to identify and take off a few clips.
• 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 P0456. 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.

Toyota Sequoia Diagnosis - P0456

To diagnose the problem with your Toyota Sequoia's P0456, a mechanic can use a variety of tools. The most commonly used methods to diagnose this code are:

• The mechanic will usually 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.
• The mechanic will normally determine what trouble codes are associated with P0456. 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.
• 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:

Most common P0456 fixes

Below are the most commonly used Sequoia P0456 solutions:

• Replacing the 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 test your gas tank.

We wish you all the best in finding out why your Toyota Sequoia is throwing the code P0456. We trust this helped. You can add any additional information by leaving a comment.

Are P0456 Serious Concerns?

While P0456 is not going to cause the Sequoia’s engine to stop running, it should not be treated lightly. There could be fuel contamination. 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.

Feel free to add anything to the article by leaving a comment. Thanks!