What Is the P0455 Code?
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The P0455 diagnostic trouble code appears when there’s a leak in the Evaporative Emission Control (EVAP) system, and the system can’t maintain pressure. The EVAP system usually consists of five main components: the fuel tank, fuel cap, vent valve, purge valve, and the evaporative canister (or charcoal canister).
The purpose of the EVAP system is to prevent fuel vapors from escaping into the atmosphere. According to some sources, around 20% of all vehicle-produced air pollution originates from vehicle fuel storage. The engine control module (ECM), therefore, will perform leak tests from time to time to make sure all parts of this system are in working order.
To do this, certain parameters must be in place. To test while parked, the vehicle and ambient temperature will be within range of each other, testing to see if fuel vapor can escape while not running. There are also tests while running. The ECM will cycle the vent control valve and purge valve to create a sealed EVAP system. In turn, the EVAP system will signal a large leak if the system can’t maintain pressure.
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What Are the Symptoms of a P0455 Code?
The most evident symptom of a P0455 code, besides the check engine light coming on, is the strong gas smell you’ll notice near the fuel tank. There aren’t any noticeable performance symptoms to your car’s engine, so it’s important to be aware of any fuel smell around your car.
What Are Some Causes of a P0455 Code?
Numerous factors might cause the leak. Most often, the leak has something to do with the fuel filler cap. It could be missing, not sealed properly, damaged, or not correctly installed. Sometimes, the P0455 code can be set while fueling incorrectly or even by failing to turn off the engine while fueling your vehicle.
Another common cause of this code triggering is leaks. Hoses (like the large one connecting the filler neck to the tank) can crack with time. The EVAP system’s purge valve is used to regulate pressure and is one of the things you should check first when you get the P0455 code. A visual inspection of readily viewable components is an efficient first step.
More possibilities include:
- Aftermarket EVAP hardware that doesn’t conform to the EVAP return tube
- The EVAP purge valve is stuck closed
- A slow-responding EVAP purge valve
- Blockages in the fuel vapor hoses or tubes
- Loose fuel vapor hose or tube connections to the EVAP system components
- A damaged fuel tank pressure sensor
Although this code refers to a “gross” (large) leak, this is an emission standard specification for a disconnected or cracked fuel EVAP canister tube or EVAP canister purge outlet tube. However, the leak may appear really small.
How Serious Is the P0455 Code?
If there’s a large leak, your car will waste more fuel. Since a fuel leak from the tank or any of the associated seals could cause the diagnostic code to set, you should pay attention to it and consult a qualified technician immediately. If they don’t detect any problems, they can reset the codes and then retest. Because a fuel leak from the tank and associated seals could cause this diagnostic code, immediate attention to the evaporative emission system is in order.
Can I Still Drive with a P0455 Code?
Yes, you can still drive with a P0455 code since it won’t affect the way the vehicle performs. However, if the fuel odors are strong and you suspect there’s a leak, take your car to a technician immediately.
How Easy Is It to Diagnose a P0455 Code?
To diagnose a leak, a technician will use an OBD-II scanner. They should record all store codes and the associate freeze frame data, reset the code and take the vehicle for a test drive to see whether the code reappears. A complete drive cycle must be completed. To perform this test, most vehicles need the fuel level to be between 15% and 85%. If the fault code returns, the mechanic needs to inspect your vehicle and search for the location of the leak.
If they can’t find any obvious leaks, they’ll use a smoke test to look for them. A smoke test is a series of tests your mechanic will perform to look for leaks in any vacuum hoses. The test can determine if any routing in the vacuum system has a leak. If there still isn’t a noticeable leak, the problem might be the sensor. In this case, the sensor needs to be tested by the manufacturer’s instructions.
How Difficult Is It to Inspect a P0455 Code?
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There are several steps your technician will need to take to repair a P0455 code. First, they will need to scan the vehicle to see whether any other codes come up. If this happens, they may need to be addressed first. Then, they’ll probably check the gas cap to see if it’s loose or damaged. If it’s loose, they will tighten it. If it’s damaged, they will probably recommend replacing it. If there are no visible signs of damage or wear to the fuel cap, with no other visible signs of leakage within the EVAP system, trying a known good fuel cap can be a time-saving step in the overall diagnosis process.
Reset the code, complete a drive cycle, and see whether the problem is solved. If not, they’ll need to perform an EVAP system leak check. You can do this by pinching off the vent tube to the EVAP Vent Control Valve and pressurizing the EVAP system with a smoke machine leak checker. This is something best left to qualified technicians with EVAP experience.
If the technician notices any leaks from any hoses or seals, you need to replace them. Afterward, they will check to see whether the problem is solved. If not, further diagnosis will be required.
Need Additional Help with Your P0455 Code?
Most likely, you won’t notice any symptoms associated with this code other than the check engine light turning on. Although your car will still be able to run, you should consult a technician and locate the cause of the problem. If you need help with your P0455 code, KBB.com can connect you with service centers in your area.
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