Hyundai Sonata P0456: EVAP System – Small Leak

The most frequent trouble code with the Hyundai Sonata The Code P0456. This is the trouble code that you get when you plug in your Sonata to an internet computer. OBDII scanner. A P0456 code indicates that there may be a slight leakage in the evaporative exhaust control system. It is sometimes found along with other codes such as P0440, P0441, or very frequently P0440.

Normally, P0456 does not pose a danger to the Sonata’s drive-ability. 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 Hyundai Sonata, it is actually referring to the amount of pressure lost, and not the physical size of the leak. They can also be very tiny.

Hyundai Sonata P0456 Definition

The universal OBDII trouble code P0456 can be used to diagnose any problem. It means that no matter what make or model vehicle you have, this code will always mean the same (Sonata). 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 it to engines intake for ignition. When there is a small leak in the Hyundai Sonata’s EVAP system, it will throw the P0456 OBDII Code. If there is a large leak, it’ll throw P0455.

Hyundai Sonata P0456 OBDII Code Symptoms

The P0456 code is usually not accompanied with any other symptoms than those listed. Smells like gas 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 Sonata's engine.

Sonata P0456 Troublecode Causes

Your Hyundai Sonata can trigger the P0456 code. If your Sonata 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 leading cause of 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 will need to locate and take out 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. 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 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.

Hyundai Sonata Diagnosis - P0456

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

• The mechanic will check for 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 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.
• 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 top Sonata P0456 solutions:

• Replacement of gas cap
• Replacement for EVAP lines
• 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 check your gas cap.

You will need to solve the problem quickly. We trust this helped. Please feel free to add anything below.

Are P0456 Serious Concerns?

While P0456 is not going to cause the Sonata’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.

Please leave comments below if you have any suggestions. Thanks!