DTC P0455: EVAP Control System Leak Detected (No Purge Flow Or Large Leak)

WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

P0455 - EVAP CONTROL SYSTEM LEAK DETECTED (NO PURGE FLOW OR LARGE LEAK)

Description:	The PCM monitors the complete 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 (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 (such as fuel filler cap) non-conforming to 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 (items also listed under disconnections or cracks). 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. Fuel tank isolation valve stuck closed.
Diagnostic Aids:	Check for audible vacuum noise or significant fuel odor in the engine compartment or near the EVAP canister and fuel tank. Check for a missing fuel filler cap or the integrity of the cap. Check for loose or damaged vapor hoses.
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
All	-	-	GO to Pinpoint Test HX .