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

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2011 Mercury Milan, 2011 Mercury Mariner, 2011 Mercury Grand Marquis, 2011 Lincoln Town Car, and 2011 Lincoln Navigator L. 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:	Aftermarket 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, missing or loosely installed fuel filler cap Capless fuel tank filler pipe damaged or not sealed correctly (if equipped) 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 EVAP canister vent solenoid stuck open (if equipped) Mechanically inoperative fuel tank pressure (FTP) sensor (if equipped)
Diagnostic Aids:	Check for audible vacuum noise or significant fuel odor in the engine compartment or near the EVAP canister and fuel tank. Verify the capless fuel tank filler pipe is sealed correctly. Install and remove the supplemental fueling adapter five times in the capless fuel tank filler pipe to clear debris on the seal. Refer to the Owner's Literature for the location of the supplemental fueling adapter in the vehicle.
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
Fiesta	GO to PINPOINT TEST HZ .
All others	GO to PINPOINT TEST HX .