DTC P0455: Evaporative Emission System Leak Detected (Gross Leak/No Flow)

WARNING: This page does not describe the selected car, but rather 30 other vehicles, including the 2006 Mercury Mountaineer, 2006 Mercury Monterey, 2006 Mercury Montego, 2006 Mercury Mariner, and 2006 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.

P0455 - EVAPORATIVE EMISSION SYSTEM LEAK DETECTED (GROSS LEAK/NO FLOW)

Description:	The powertrain control module (PCM) monitors the complete evaporative emission (EVAP) control system for no purge flow, the presence of a large fuel vapor leak, or multiple small fuel vapor leaks. System failure occurs when no purge flow, which is attributed to fuel vapor blockages or restrictions, a large fuel vapor leak, or multiple fuel vapor leaks are detected by the EVAP running loss monitor test with the engine running, but not at idle.
Possible Causes:	After market EVAP hardware that does not conform to the required specifications Disconnected or cracked fuel EVAP canister tube, EVAP canister purge outlet tube, or EVAP return tube EVAP canister purge valve stuck closed Damaged EVAP canister Damaged or missing fuel filler cap Insufficient fuel filler cap installation Loose fuel vapor hose/tube connections to the EVAP system components Blockages or restrictions in the fuel vapor hoses/tubes Fuel vapor control valve tube assembly or fuel vapor vent valve assembly blocked Canister vent (CV) solenoid stuck open Mechanically inoperative fuel tank pressure (FTP) sensor
Diagnostic Aids:	Check for audible vacuum noise or significant fuel odor in the engine compartment or near the EVAP canister and fuel tank.
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
All	-	-	GO to Pinpoint Test HX .