P0455 – Meaning, Causes, Symptoms, & Fixes
Code P0455 Definition
System gross leak evaporative system malfunction
Code P0455 Meaning
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. Both the vent control valve and the purge valve are usually open when the engine is at normal operating temperature. However, the ECM occasionally performs leak tests to ensure the evaporative emission control system is working properly. During the leak test, the ECM closes the vent control valve and purge valve to create a vacuum. 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.
- Check Engine Light is on
- Decreased fuel economy
- Fuel smell
- Loose or damaged gas cap (*Most Common)
- Faulty or stuck vent control valve
- Faulty or stuck purge valve
- Cracked or disconnected EVAP hose
- Cracked or damaged charcoal canister
Code P0455 Severity – Low
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 leak in the airbox hose. The system leakage can cause an excessive amount of fuel consumption if not taken care of shortly after.
Code P0455 Common Diagnosis Mistakes
Many people fail to follow the full diagnostic test and can underpay or even overpay for their solution. Fuel caps ($) are the easy fix with a run to your local auto repair shop, but people sometimes neglect the possibility of other components it might possibly be which are more costly ($$).
Code P0455 Diagnosis Steps
Tools Needed to Diagnose:
How To Diagnosis
- 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 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 check 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 are not always noticeable. If your gas cap was not loose and you do not see any indications of failure, try replacing the gas cap anyways and clearing the codes. Gas caps are relatively inexpensive and are usually the fix for code P0455.
- Check for cracked or disconnected EVAP hoses near or connected to engine air box
- Replace cracked/disconnected hoses
- Clear code*
*If code returns, you will need to be given further diagnostics at a mechanic. More diagnostic steps could require electrical testing of the purge and vent control valves for proper operation. It may also require a smoke machine test to detect and find a leak in the system.