Ford Focus P0455: EVAP System → Leak Detected (Large)

The most frequent trouble code with the Ford Focus Is the Code P0455. This code is used to refer to the trouble code for your Focus that you get when it's plugged in to an OBD2 scanner. The number has to do to with the emissions system. The P0455 code indicates that the emission system is malfunctioning. Leakage large In the evaporative emissions control system (EVAP). It is frequently found alongside, or closely related to, other codes like P0420/P0430, P0441 and, very often, P0440.

P0455: EVAP System → Leak Detected (Large)

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

Ford Focus Definition P0455

P0455 refers to a general OBDII trouble code. It means that no matter what make or model vehicle you have, this code will still mean the same thing. The code is technically:

System Gross Leak Evaporative Emission System

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

Ford Focus OBDII Code Symptoms P0455

A P0455 Code will usually not cause any symptoms except the ones listed below. Smells like gas The service engine soon light. The slightest drop in fuel economy may also be noticeable.

The fuel tank and fuel filler tubes should smell particularly strong.

Fuel vapors are dealt with directly by the EVAP system. If these vapors are leaking from the system, you’ll often smell them faintly while operating the vehicle.

Problem Codes Focused P0455

P0455 code may be activated in Ford Focus due to many reasons. The most frequent problems that trigger this code are:

• Evap 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 P0455 code. You should look for a hole or a tear in the code. This is one of most frequent causes for the 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.
• The Faulty Charcoal Caister– 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. 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 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.

Ford Focus Diagnostics - P0455

The mechanic will have a lot of different tools at his disposal in order to determine the cause of your Ford Focus P0455. 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 P0455. Check out 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 Ford Focus, 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

Below are the top Focus P0455 solutions:

• Replacement of gas cap
• Replacing 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 find the cause of your Ford Focus throwing the code P0455. This should help. Please feel free to add anything below.

Do you consider P0455 to be a serious concern?

While P0455 is not going to cause the Focus’s engine to stop running, it should not be treated lightly. Fuel leaks could be a problem. Check your tank regularly to make sure there is no fuel leaking. It is best to have it checked and/or dealt with immediately.