Nissan Frontier P0456: EVAP System – Small Leak

This is one of the most commonly encountered trouble codes for the Nissan Frontier The Code P0456. The trouble code refers to a number you receive when your Frontier is plugged into an a OBDII scanner. The code P0456 indicates that the evaporative emissions control system has a tiny leak. This code is often found with or related to P0441 and P0420.

Normally, P0456 does not pose a threat to your Frontier'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 Nissan Frontier, it is actually referring to the amount of pressure lost, and not the physical size of the leak. They can also be very tiny.

Nissan Frontier P0456 Definition

P0456 stands for a universal OBDII Trouble Code. It means that no matter what make or model vehicle you have, this code will still mean the same thing. Technically speaking, it stands for:

System Leakage of Small Size – Evaporative Emission System

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

Nissan Frontier P0456 OBDII Code Symptoms

A P0456 Code will not usually be associated with other noticeable symptoms. The smell of gas And the service engine soon light.

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. 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 Frontier's engine.

Frontier P0456 Trouble Code Causes

P0456 can occur for many reasons in your Nissan Frontier. If your Frontier 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.

Below are the top most probable problems that could throw the code. These were listed alphabetically, in some order.

• Evap System Hose– The hose that carries the fuel vapor from the fuel tank to the intake manifold can begin to leak. The P0456 error code will be generated. 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. 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. It can lower the tank pressure, which could throw out the code.
• Capacity for Fuel– 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. 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.

P0456 Diagnosis- Nissan Frontier

To diagnose the problem with your Nissan Frontier's P0456, a mechanic can use a variety of tools. These are some of the common diagnostics that can be done for the code.

• The mechanic will check to make sure there are no other 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. 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.
• 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:

The Most Popular P0456 Fixes

Below are the top Frontier P0456 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 Nissan Frontier is throwing the code P0456. This should help. Please feel free to add anything below.

Do you consider P0456 to be a serious concern?

While P0456 is not going to cause the Frontier’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. You should immediately take it in for repair or replacement.

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