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.

EVAP pressure sensor and MAP/BARO sensor circuits are monitored by PCM. Leak test fails when intake vacuum is applied to EVAP system through EVAP canister purge valve with EVAP canister vent control solenoid closed and EVAP pressure sensor signal to PCM does not match that of MAP/BARO sensor signal to PCM. Possible causes are as follows:

Leak in the line between the intake manifold and the 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.
Blocked or bent hose to the 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 P0440, disconnect hoses from MAP/BARO and EVAP pressure sensors. Turn ignition on. Both MAP/BP_V and EVAPRES PIDs should indicate the same voltage.