What Does P0455 Code Means On The Car?

P0455 code will not affect the way the car drives, but if the fuel odors are very strong or have obvious fuel leaks, take the car to a qualified technician as soon as possible. The system leak failure can cause excessive fuel consumption in certain circumstances so it is best to take it to a technician at your first opportunity. Occasionally, if no problems are found, the technician can reset the fault codes, then retest.

To do proper testing of the fuel tank, it should be 1/4 to 3/4 full to ensure proper conditions to test. Oftentimes, in case the Check Engine Light came on immediately at startup, the OBD-II system can be reset and the vehicle will operate normally.

Oftentimes, in case the Check Engine Light came on immediately at startup, the OBD-II system can be reset and the vehicle will operate normally.

What Does Code P0455 Mean?

The evaporative emission control (EVAP) system prevents fuel vapors from escaping into the atmosphere. The fuel vapors from the fuel tank are absorbed and stored by charcoal pellets in the charcoal canister. The vent control valve is controlled by the engine control module (ECM) and allows air to flow into the charcoal canister to purge the gas vapors into the engine air intake to be burned. The flow of the gas vapors from the charcoal canister to the engine air intake is controlled by a purge valve.

The vent control valve is normally opened when the engine is on. The purge volume control valve is normally closed. And it is controlled by the ECM to open when it is ready to purge the stored fuel vapors from the charcoal canister.

However, the ECM occasionally performs leak tests to ensure the evaporative emission control system is working properly when the vehicle is turned off. During the leak test, the ECM closes the vent control valve to create a sealed EVAP system. If the EVAP system does not maintain the pressure, the ECM recognizes an evaporative emission control leak. In the case of P0455, it is a very large leak. This is usually indicative of a loose, broken, or missing gas cap.

What Causes The P0455 Code?

There are several causes of getting the P0455 Code but most of the common causes are

1. Fuel Filler Cap

The leak can cause by a variety of components. The most common is related to the fuel filler cap. It could be missing, not correctly installed, not sealing properly, or maybe damaged to the top of the filler neck.

2. Leak In A Hoses

The next most frequent problem is a leak in a hose. Hoses on the breather system tend to crack with age including the large connecting hose on the filler neck to the tank. The Evaporative Emission System has a purge valve to regulate pressure in the system and this will need to be checked by a technician.

3. Leak In A Filter

Vehicles with a charcoal filter on their evaporative system need to check the filter for cracks, damage, or leaks. The fuel tank itself may be leaking or the gasket where the fuel level sensor, pressure sensor, and fuel pick attach to the tank may be leaking. See the manufacturer’s diagram of the system to verify components and their locations in the manual book of the car. Note that even if the code indicates a large leak, it may actually be fairly small.

How can I fix a P0455 problem and where should I start?

In case you face the problem with P0455 Code problem, follow the below steps to diagnose.

1. Check Gas Cap For Proper Tightness

Ensure your vehicle’s gas cap is properly sealed. Make sure when closing the cap you hear the right number of clicks. In case you find the gas cap to be loose or the gas cap’s seal to be broken or brittle, then more than likely your problem is solved. Replace the cap with a new one or tighten the cap, depending on the problem you find, then drive your vehicle for the next few days as normal.

The check engine light should turn off on its own and the trouble code erase from memory after a few drive cycles. A drive cycle is typically considered one full engine on and engine off cycle. The vehicle is driven for at least 30 miles and then parked for at least 8 hours. In case you have access to an OBD-II scan tool, you can manually turn off the check engine light. Erase the P0455 trouble code and see if the check engine light will turn back on.

2. Check Gas Cap Rubber Seal For Cracks

Should you find that the gas cap was tight and the seal appears to be in good condition, further diagnosis will be required. You will then need to inspect all EVAP hoses leading from the gas tank to the charcoal canister. And from the charcoal canister to the engine air intake usually the air cleaner assembly. Finding the EVAP hoses may or may not be difficult. In case you can locate the EVAP canister usually near the gas tank, you can follow the hoses leading to the engine compartment and gas tank. Look for breaks and disconnections in the lines.

3. Check all EVAP hoses leading to and from the charcoal canister

If the EVAP hoses too appear to be in good condition, not loose and not disconnected. The next step will require the use of proper diagnostic tools. And best left to a technician to handle. Typically to find a fuel vapor leak, a smog technician would test the entire EVAP system using an OBD-II scan tool and smoke machine. The smoke machine places smoke in the EVAP system. Leaks can then be visually detected.

4. Diagnose Both The Purge And Vent Control Valves

Diagnosis may also require electrical testing of the purge valve and the vent control valve for proper operation.

What Will It Cost To Resolve A P0445 Code?

Most shops will charge a diagnostic fee, usually around 100$. Unlike smaller leaks, which can require more diagnosing, a gross leak is usually found quickly. Because these leaks go beyond small pinholes in rubber hoses, repairs can get costly. A missing gas cap might cost you 25$.

But to change a vent valve or purge valve, the price can run around 200$–300$, depending on parts availability. A charcoal canister repair will run 400$–600$, depending on where it is located. The cost to replace a filler neck can run from 300$ to 400$.


Many vehicles with mileage over 100,000 have momentary sensor problems that usually occur during start-up or prolonged stress situations on the drive train. If the Check Engine Light comes on and the vehicle seems to be operating normally, the OBD-II system can be reset using the scanner and the problem may not reoccur. This is why it is important to verify the fault and reset it before doing any repairs.

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