Diagnostic Aids
WARNING: This page is about a different car, the 2002 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.
- DTC P0455: EVAP Emission Control System Leak Is Detected (No Purge Flow Or Large Leak)
DTC P0455 indicates no purge flow, presence of a large fuel vapor leak or multiple small fuel vapor leaks. System failure occurs when no purge flow (attributed to fuel blockages or restrictions), a large fuel vapor leak or multiple fuel vapor leaks are detected by EVAP running loss monitor test with engine running (but not at idle). Possible causes are as follows:- Aftermarket EVAP hardware (such as fuel filler cap) non-conforming to required specifications.
- Disconnected or cracked fuel EVAP canister tube, EVAP canister purge outlet 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 EVAP system components.
- Blockages or restrictions in fuel vapor hoses, tubes or EVAP components.
- Vacuum cut valve blocked.
- EVAP canister vent control solenoid stuck open.
- Inoperative EVAP pressure sensor.
For DTC P0455, check for audible vacuum noise or significant fuel odor in engine compartment or near EVAP canister and fuel tank. With no pressure applied to EVAP pressure sensor EVAP PS PID should read 3.0-3.6 volts.
- DTC P1440: EVAP Emission Control System Leak Detected (Small Leak - Positive Pressure)
DTC P1440 is indicated with fuel tank fuel vapor pressure applied to EVAP system through EVAP vacuum cut by-pass valve, while EVAP canister vent valve is closed and EVAP canister purge valve is closed, leak test fails when EVAP pressure sensor signal to PCM does not rise accordingly to calculated fuel vapor pressure obtained from fuel tank temperature sensor signal sent to PCM. Possible causes are as follows:- Incorrect fuel tank vacuum relief valve.
- Incorrect fuel filler cap used.
- Fuel filler cap remains open or fails to close.
- Foreign matter caught in the fuel filler cap.
- Leak in line between intake manifold and EVAP canister purge valve.
- Foreign matter caught in EVAP canister vent control solenoid.
- EVAP canister or fuel tank leaks.
- EVAP purge line leaks.
- EVAP purge line bent.
- Blocked or bent line to EVAP pressure sensor.
- Loose or disconnected rubber tube.
- EVAP canister vent control solenoid or circuit.
- EVAP canister purge valve or circuit.
- MAP/BARO pressure sensor or circuit.
- MAP/BARO solenoid valve or circuit.
- Fuel tank temperature sensor.
- Blocked or bent hose to MAP/BARO pressure sensor.
- "O" ring of EVAP canister vent control solenoid is damaged or missing.
- Water separator.
- EVAP canister is saturated with water
- EVAP pressure sensor.
For DTC P1440, close EVAP canister purge valve, EVAP canister vent valve, open vacuum cut by-pass valve, apply 0.2-0.4 psi (1.37-2.76 kPa) pressure to EVAP emissions test port. EVAPRES PID should increase from EVAPRES PID value with no pressure applied to EVAP system.