You can find information about the P0455 fault code on this page.
It is one of the most popular fault codes that people search for on this website (in the top 50).
We have given it a seriousness of 4/10 with 1 being the least serious and 10 being the worst.
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The code P0455 is logged when a large leak in the evaporative emission control system (EVAP) is detected.
This does not necessarily mean that there is a leak in the actual fuel system of the vehicle, only the EVAP.
The purpose of the EVAP system is to prevent fuel vapors from being released into the atmosphere. This is done to comply with emissions requirements and has been a requirement since the 1970s.
The EVAP system itself does not strongly influence the day-to-day operations of a vehicle.
Other Signs of This Problem
There are very few signs that could indicate a leak in the EVAP system, making it hard to determine without the error code.
In fact, cars can operate fairly well even with a leak and did so before these systems became a requirement by law.
The most obvious sign is that the Check Engine light will be on.
There could potentially be a distinct gasoline smell if you park in a confined space like a garage.
Look out for any other codes relating to the EVAP system. These are fault codes like P0440, P0441, and P0456. You may find P0456 is logged before P0455 as this indicates a smaller leak that has grown worse.
What Could Be The Problem?
While diagnosing issues with a vehicle’s EVAP system can be notoriously difficult, there is one very simple component in the system that could be causing problems: the gas cap.
A faulty, loose, or damaged gas cap can cause this P0455 error, as well as any other EVAP system error codes. This fault can also be a sign of damage or wear in the fuel hose.
Additionally, there could be an issue with components like the EVAP vent control valve or purge volume control valve.
It is very important to take utmost care when dealing with any issues with the fuel tank as there are highly flammable fumes present.
The simplest fix for this type of issue is to check your gas cap. If a gas cap has not been fastened properly, the vehicle’s computer can detect a leak, triggering the P0455 fault code.
Additionally, a damaged or faulty gas cap can also prevent a proper seal from being formed. This allows a leak of fuel vapors into the vehicle’s surrounding atmosphere. Be sure to check the fuel cap seals are still in good order.
If there are no noticeable issues with the gas cap, a specialist diagnostic tool called a ‘smoke machine’ is required for fault-finding elsewhere in the EVAP system.
Fault code P0455 ranks very low in terms of severity. There is practically no risk of damage to yourself or the vehicle.
It should be fixed to prevent losses in the fuel tank, ideally within a few weeks.
This does bump up in seriousness if your vehicle has an upcoming emissions test, as this can easily cause the vehicle to fail. It also should be fixed soon if you park in a garage to prevent your garage from being filled with dangerous fuel vapors.
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