Fault code P0455 – a step-by-step guide to diagnosing and fixing it

Error code P0455 is displayed and the check engine light is on - what does this mean?

The OBD system has detected a major leak in the evaporative emission control system (EVAP). This DTC P0455 indicates a significant leak that is preventing the system from building up the required vacuum. With various manufacturers, this fault code can also be referred to as "Evaporative Emission Control System Leak Detected (gross leak)".

What can cause this error code?

• Defective or missing fuel filler cap
• Damaged fuel lines in the EVAP system
• Defective purge valve (purge valve)
• Leaking activated charcoal canister vent valve
• Cracks in the activated charcoal container
• Damaged vacuum lines
• Defective fuel pump or its seals
• Corroded or loose hose clamps
• Leaking fuel tank
• Defective pressure sensor in the EVAP system

What symptoms occur in parallel with fault code P0455?

• Fuel odor: smell of gasoline, especially when refueling or when the engine is warm
• Increased fuel consumption: Noticeably higher consumption due to fuel loss
• Starting problems: Difficulties with cold starts, especially in the morning
• Power loss: Reduced engine power at higher engine speeds
• Check engine light: Permanently illuminated check engine light
• Emission test problems: Vehicle does not pass emissions test

How can the problem with error code P0455 be rectified?

• The repair requires a systematic check of the entire EVAP system, starting with the simplest solutions.
• Check and replace the fuel filler cap: Check the gas cap for cracks or damaged seals and replace if necessary - this is the most common and cost-effective solution
• Inspect EVAP lines for leaks: Perform a visual inspection of all vacuum lines and completely replace any damaged or porous hoses
• Test and replace purge valve: Check the valve for proper function using a multimeter and replace if defective
• Replace the activated charcoal container and purge valve: Check the charcoal canister for cracks and the vent valve for proper function, replace both components if damaged
• Have the fuel tank professionally checked for leaks: Have a pressure test of the tank carried out at a specialist workshop and seal any leaks or replace the tank
• Complete EVAP system diagnosis with smoke test: Hire a garage to perform a professional smoke test to locate and fix even the smallest leaks