DTC P0440: EVAP Circuit, Malfunction, Or DTC P0455: EVAP Circuit, Large Leak Detected: Condition

With engine running, Power Control Module (PCM) closes EVAP canister air valve and opens EVAP canister purge valve. If EVAP control system is okay, EVAP control system pressure detected by fuel pressure sensor is lowered. When EVAP control system pressure is lowered, PCM closes EVAP canister purge valve, leaving EVAP canister air valve closed. If EVAP system is okay, fuel tank pressure will increase to a predetermined level.

DTC P0440 is set when fuel tank pressure increase exceeds a predetermined value. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. DTC P0455 is set when fuel tank pressure change is less than predetermined. MIL is illuminated when PCM detects malfunction during first drive cycle. Possible causes are:

• Missing, loose or malfunctioning fuel filler cap.
• Loose or plugged vacuum hose.
• Components mounted to fuel tank leaking in aria of mounting.
• EVAP canister plugged.
• EVAP canister purge valve malfunction.
• EVAP canister air valve malfunction.
• Fuel tank pressure control valve malfunction.
• On vehicles not equipped with On-board Refueling Vapor Recovery (ORVR), fuel tank pressure control solenoid valve malfunction.
• Fuel Tank Pressure (FTP) sensor malfunction.
• Fuel level sensor malfunction.
• PCM malfunction.