Toyota Tacoma P0456: EVAP System – Small Leak

This is one of the most commonly encountered trouble codes for the Toyota Tacoma The Code P0456. The trouble code refers to a number you receive when your Tacoma is plugged into an a OBDII scanner. A P0456 code indicates there may be a slight leakage in the evaporative exhaust control system. It is sometimes found along with other codes such as P0441 or P0420.

Your Tacoma's driveability is generally not affected by P0456. 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 Tacoma, 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 Tacoma P0456 Definition

The universal OBDII code P0456 can be used to diagnose trouble codes. The code can be used regardless of the make and model of your vehicle. Technically speaking, it stands for

System Leakage of Small Size – Evaporative Emission System

The EVAP system collects fuel vapor from your fuel tank, and then sends it to the intake to ignite the engine in normal combustion. When there is a small leak in the Toyota Tacoma’s EVAP system, it will throw the P0456 OBDII Code. If there is a large leak, it’ll throw P0455.

Toyota Tacoma P0456 OBDII Code Symptoms

The P0456 code is usually not accompanied with any other symptoms than those listed. Smells like gas And the service engine soon light.

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

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. But, it won’t affect the way the engine itself runs. The EVAP system is for fuel vapor and does not affect the operation of your Tacoma's engine.

Tacoma P0456 Trouble Code Causes

P0456 can happen for many reasons in your Toyota Tacoma. If your Tacoma 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. This can lead to the code P0456. 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 P0456 code is the vapor canister purge valve. It’s really easy to replace. There are some clips you will need to look for and then remove.
• 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. It may be worth your time to get that message and a P0456 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. 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.

Toyota Tacoma Diagnosis - P0456

To diagnose the problem with your Toyota Tacoma'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. 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 P0456. Take a look at 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.
• 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:

Most common P0456 fixes

Below are the top Tacoma P0456 fix requests:

• Replacement of gas cap
• Replacement for EVAP Line
• 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 Toyota Tacoma is throwing the code P0456. This should help. You can add any additional information by leaving a comment.

Are P0456 Serious Concerns?

While P0456 is not going to cause the Tacoma’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.

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