P0455 – Meaning, Causes, Symptoms, & Fixes
Code P0455 Definition
The vehicle has detected a large evaporative system leak.
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, and the purge volume control valve is normally closed and 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 Are The Symptoms Of Code P0455?
- Check Engine Light is on
- Decreased fuel economy
- Fuel smell
What Is The Cause Of Code P0455?
- Missing, defective, damaged, or loose cap (*Most Common)
- Faulty or stuck EVAP vent control valve
- Faulty or stuck EVAP purge volume control valve
- Cracked or disconnected EVAP hose
- Cracked or damaged charcoal canister
How Serious Is Code P0455? – Low
The driver will likely not notice any symptoms associated with P0455 other than the check engine light being on. If the fuel odor is very strong and it is apparent that there are leaks, take your vehicle to your repair shop as soon as possible. The most common problems with code P0455 is a loose gas cap or cracked EVAP hose.
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Code P0455 Common Diagnosis Mistakes
Many people fail to perform a smoke test before or after replacing the fuel cap and jump straight to component replacement. The problem could be as simple as a loose or cracked EVAP hose.
Tools Needed to Diagnose Code P0455
How To Diagnose And Repair Code P0455:
Difficulty of Diagnosis and Repair – 2 out of 5
- Scan your vehicle to verify P0455 is the only code present. If other codes are present, they must be addressed first.
- If you have code P0441, P0440, or code P0456, the cause of the codes is most likely a solenoid failure, or a more complex system leak. These issues must be addressed first.
- Check your gas cap to see if it is loose or damaged.
- If your gas cap is loose, tighten it and clear the code.
- Inspect your gas cap for physical damage or deterioration. However, it should be noted that damage to the gas cap or deterioration of its components is not always noticeable. If your gas cap was not loose and you do not see any indications of failure, try replacing the gas cap anyway and clearing the codes. Gas caps are relatively inexpensive and are usually the fix for code P0455.
- If the fuel cap didn’t fix it, perform an EVAP system leak check:
- Pinch off the vent tube to the EVAP Vent Control Valve.
- Pressurize the EVAP system with an EVAP smoke machine leak checker.
- Check to see if you see any smoke leaking out from any hoses or seals. If there are any leaks, repair leaks, cleared the check engine light, and check to see if the concern is resolved.*
*If code returns, you will need to be given further diagnostics by a mechanic. More diagnostic steps could require electrical testing of the purge and vent control valves for proper operation.
Estimated Cost of Repair
For error code P0455, one or more of the below repairs may be needed to solve the underlying issue. For each possible repair, the estimated cost of repair includes the cost of the relevant parts and the cost of labor required to make the repair.
- Gas Cap $20-$60
- EVAP Line $20-$100
- EVAP Vent Control Valve $150-$200
- Purge Volume Control Valve $150-$200