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Engine Light Code P0455

new 6/05/2004

Only been driving my SHO for day #5, and got a service engine soon light this morning :( Hooked up the scanner, gave me code " P0455 EVAP Emission Control System Leak (Large) ". Not sure where to start with that one. But wondering if that has any correlation to the very slight roughness at idle....? Any thoughts and help would be much appreciated, Thanx!!

Adam Phillips

Sounds like your gas cap is leaking air.


Continuous Memory Diagnostic Trouble Code (DTC) P0455 indicates that the Evaporative Emission (EVAP) control system detected a large leak or no purge flow.

Possible causes:

After market parts and accessories nonconforming to the EVAP system specifications.
Damaged, missing or improperly installed fuel filler cap.
Blockage in fuel vapor hoses/tubes (EVAP canister tube, EVAP canister purge outlet tube or EVAP return tube) in EVAP system.
Disconnected or cracked fuel vapor hoses/tubes in EVAP system.
EVAP canister purge valve stuck closed.
Canister vent (CV) solenoid stuck open.
Fuel tank pressure (FTP) sensor malfunction.
EVAP canister leaking.
Fuel vapor control valve tube assembly blocked.
Fuel vapor vent valve assembly blocked.
Check for missing fuel filler cap. If the cap is loose DO NOT DISTURB EVAP system.
Verify that both the input port vacuum hose and EVAP return tube are attached to the EVAP canister purge valve.
Note: If the EVAP canister-CV solenoid assembly is not accessible to perform the following step, Go to the Powertrain/Engine Group, Evaporative Emissions Section in the Workshop Manual for removal and installation procedures.

Verify that the CV solenoid is properly seated on the EVAP canister (if possible).
Visually inspect for disconnected or cracked fuel vapor hoses/tubes between the intake manifold, the EVAP canister purge valve, the EVAP canister, the fuel vapor vent valve assembly and if applicable the fuel vapor control valve tube assembly.
Check for damage to the fuel filler pipe and the fuel tank.

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