P0440

Schematic:

Once every drive cycle, the EVAP System run a 25-40 second diagnostic where it monitors possible leaks, the fuel tank pressure sensor, vent value and canister purge value. This diagnostic has 5 phases and can set several different codes depending on which part of the diagnostic fails. If in the first phase, the tank pressure is too slow to reach a certain value, this code will set. It can also set in the third phase if the tank pressure falls too slowly when the vent and purge are both opened. This code indicates that the vent value is either blocked open or closed.

DTC PARAMETERS
DTC P0440 will set when:
^ Vehicle speed = 0 mph
^ Engine speed = idle
^ Fuel System in closed loop
^ Battery voltage greater than 11.05 volts
^ Engine run time greater than 1 min. 45 sec.
^ Altitude less than 9000 ft.
^ Fuel level between 1.85 and 14 gal.
^ NO TP, ECT, VSS, tank pressure, oxygen sensors, idle control, purge value, vent value, battery voltage, misfire, and EGR codes set.

DTC P0440 is a (type B) DTC.

DIAGNOSTIC AIDS
Possible causes:
^ EVAP vent solenoid stuck closed
^ Vent hose allowing atmospheric pressure into EVAP canister
^ EVAP vent solenoid circuit 1310 intermittently shorted to ground or ECM intermittently shorted to ground internally on that circuit.