P0455 Code: EVAP System Large Leak Detected (Causes & Fixes) (2024)

Every modern vehicle has many sensors that monitor the overall work of the systems and components. When the engine control module detects a wrong value during testing or measurement, it sends a fault code. There are hundreds of different codes and it is difficult for a driver to understand them. The P0455 is just one of the engine codes that needs decoding.

The P0455 code is a result of a large leak in an Evaporative Emissions Control System (EVAP). The purpose of that system is to keep the fuel fumes inside the fume lines. If there is a leak in the system, the fumes will end up in the atmosphere causing additional pollution.

There are several error codes that are a result of an EVAP leak. The P0455, unlike the P0442 code which is a sign of a smaller leak, shows a massive EVAP leak. They can be a sign of leaks in multiple places in the system. Often the only visible sign for this error is a check engine light. To learn how to manage this error, stay with us.

Understanding the P0455 OBD2 Code in Layman’s Terms

Every car has an EVAP system. Its purpose is to stop the fuel vapors from exiting into the atmosphere. This system is essential in lowering the emissions of every vehicle. The EVAP system works closely with the fuel system to maintain the emission levels low.

Besides the regular parts of the fuel system, like fuel lines, and a fuel tank, there are several critical parts of the EVAP system. Those are the EVAP canister (charcoal canister), the canister purge valve, and the EVAP hoses and lines.

Vent lines from the fuel tank pass the fuel fumes to the EVAP canister. In the EVAP canister are charcoal pellets. Fuel fumes are stored in those pellets until the engine is started. After starting and warming the engine, the canister purge valve opens the EVAP canister and releases the fumes. They are moved into the engine intake manifold. There the fumes are burned with the rest of the air/fuel mixture.

The Basics of OBD and Error Codes

The need for standardizing error diagnostic and detection has existed for decades. Some manufacturers design their diagnostic systems. The OBD system is the first to bring standardization into this area. From 1996, every vehicle in the US has to have an OBD system of diagnostic code.

Since then, the system has had a revision called an OBD-II system. Today, with the help of an OBD-II scan tool, every driver can scan their vehicle. This system made error detection much easier since almost every component has its sensors.

When the car’s computer detects a strange value, it will send an error message. After scanning with the OBD-II scanner, it will show errors. With some help, anyone can know what part of the vehicle has a problem.

Decoding the P0455 Code: What It Means for Your Vehicle

The P0455 error code is one of those codes that don’t come with performance issues. The vehicle will run as usual, with the possibility of a small decrease in fuel economy. The biggest impact of a problem with an evaporative emission control system is the rise of bad emissions.

Common Symptoms of a P0455 Code Issue

The list of symptoms is not long, but that is not a reason to ignore this problem. It can be hard to detect this problem, so pay attention to these symptoms:

• Check engine light will turn on
• There will be an increase in fuel consumption
• The car will fail the emission test
• When parked in a closed space you may notice the smell of fuel.

Unusual Performance Indicators in Your Vehicle

Unlike problems with misfiring when there are several performance issues, with this error, you won’t notice much. The engine will work as usual, and the only thing that you may notice is fuel economy issues. Also worth mentioning is that the vehicle will not pass the emission tests.

Noteworthy Physical Signs of a P0455 Code Problem

The most obvious physical sign of a P0455 code is the smell of fuel vapors. If the leak is massive, you will notice this in an everyday drive. In other cases, the only way to notice this is when parking in a closed area.

Causes and Diagnosis of the P0455 Code

When experiencing an EVAP leak of any kind, the first thing to do is to check the EVAP and the fuel systems.

Typical Causes Behind a P0455 Code Alert

The only cause that can trigger a P0455 code is a complex EVAP leak. These EVAP vapor leaks can be caused by leaks in several parts of the system or by one big leak.

• Damaged or faulty gas cap seal
• Damaged or loose gas cap
• Blocked or damaged EVAP vent control valve
• Clogged or damaged EVAP purge volume control valve
• Loose, damaged, or disconnected EVAP hose
• Faulty charcoal canister
• Damaged fuel tank
• Faulty leak detection pump

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Diagnostic Procedures for Identifying a P0455 Code

The diagnostic procedure is similar for all cars. To be sure, check the manufacturer’s manual. It is best to start with easy steps and then move to more difficult tests.

1. Check the vehicle with the OBD-II scanner. If there are additional trouble codes, address them first.
2. Visually inspect the fuel cap. In some cases, the damage is hard to notice. That is why we recommend changing the fuel cap. This is a cheap fix, and it may resolve your issue.
3. Check the EVAP line and hoses going to the airbox for any damage. Sometimes, they can be disconnected or loose. If there is any visible damage, replace them immediately. If they are loose, use zip lines to secure them in place.
4. Inspect the fuel tank for leaking. It may show signs of corrosion or external damage. If the fuel is leaking, replace the tank immediately.
5. Check the charcoal EVAP canister. If it is damaged, replace it.
6. Examine the purge volume control valve. They can become sticky, which can also cause a leak. Test it and try to close it. If it is stuck open, replace it.
7. Investigate the vent control valve. It may show the same symptoms as the purge volume control valve. It should be able to open and close regularly. If it fails, replace it.
8. Do a fuel vapor leak test with a smoke leak detector machine. These machines can be bought for $100, but you can go to the auto repair shop for this step.

Practical Steps to Fix a P0455 Code Issue

The first and most important thing is to diagnose the problem. Check for any other error codes with the code reader so you know that the leak is the only issue. When you are certain about this, you can move forward.

Proceed with the inspection of the EVAP system and look for anything unusual. First, look at the fuel cap. That is the most common reason for this error. Next, check the EVAP lines. There can be obvious damage that is the cause of the leak.

The more complex part of the diagnostic is checking the valves. If you are not a DIY mechanic, you can leave this to the mechanic. Also, it is important to check the fuel tank. It is an expensive part to replace, but if it is leaking, that can be dangerous.

After the inspection, clear the codes with the OBD-II scan tool and go for a test drive. Wait and see will the error and the check engine light come back. If it does, it may be the best solution to visit a mechanic.

Immediate Remedies for a P0455 Code Detection

Without knowing the underlying issue, you cannot fix the problem. Sometimes a new gas cap may fix this issue, but without the proper diagnosis, you cannot get rid of a P0455 code.

Long-Term Solutions to Prevent P0455 Code Recurrence

The best way to prevent the P0455 is regular and proper maintenance. Talk with your mechanic and tell them to inspect all the parts of the EVAP system regularly. Replace the filters and fluids regularly. If you notice any fuel vapor smell, do not wait to do something. Do not get in a situation to find out about this error after failing the emission test.

FAQs About the P0455 Code

What Would Cause a Large EVAP Leak?

There are several causes for a large EVAP leak, and the most common are:

• Bad or loose gas cap
• Bad EVAP canister vent control valve
• Damaged EVAP line.

Can an EVAP Leakage Affect Gas Mileage?

Yes, an EVAP leakage can affect gas mileage. The vapors from the EVAP canister would be used in the combustion. If there is a leak in the EVAP system, additional fuel must be used to move the vehicle.

Can a P0455 Code Clear Itself?

No, a P0455 code cannot clear itself. The problem will remain until the underlying issues are resolved. It is best to resolve an EVAP problem because you will not be able to pass the emission tests. Also, your vehicle will send higher levels of bad emissions into the atmosphere.

Can I Still Drive with a P0455?

Yes, in most cases, you can still drive with a P0455 code. But, if you notice an intense fuel smell inside the car, go straight to the mechanic. Fuel vapors can be very dangerous if left unattended. In any case, do not wait too long to address this error code. Fix any EVAP vapor leaks as soon as possible.

How Much Is the Cost to Fix the P0455 Code?

The cost to fix the P0455 code depends on the problem that is causing it:

• Gas Cap Replacement: $20-$60
• Purge Volume Control Valve: $150-$200
• New EVAP Line: $50-$100
• Charcoal Canister: $200-$600
• Charcoal Canister Vent Control Valve: $150-$200
• Leak Detection Pump – $150-$450
• Fuel tank – $750-$1,500.

On these costs, you need to add the price of labor, which can vary between $75 and $150.

Need More Help with a P0455 Code?

Depending on the issue, the P0455 code can be easy and difficult to diagnose and fix. There are easy fixes like the fuel cap or the loose EVAP lines. But, there are other more advanced fixes, like a new fuel tank or other components of the EVAP system.

In most cases, you can drive with a P0455 code. But we advise you to fix it as soon as possible. Do not wait for the emission test to resolve this issue. You should not drive a vehicle that has problems with fuel vapors for too long.