P0442

Schematic:

Once every drive cycle, the EVAP system runs a 25-40 second diagnostic where it monitors possible leaks, the fuel tank pressure sensor, vent value and the canister purge value. This diagnostic has 5 phases and can set several different codes depending on which part of the diagnostic fails. The evaporative emission system is tested by applying pressure (vacuum) to the system and monitoring pressure decay. The ECM monitors the vacuum level through the fuel tank vapor pressure sensor. In the fifth phase of the diagnostic, the EVAP vent solenoid is commanded closed (normally open valve) and the EVAP canister purge valve is commanded to a fixed duty cycle, allowing the engine to draw a vacuum on the entire evaporative emission system. After a calibrated vacuum level is achieved, the EVAP canister purge valve is turned Off, sealing the system. A leak is detected by monitoring for a decrease in vacuum level over a calibrated period of time, while keeping all other variables constant.

DTC PARAMETERS
DTC P0442 will set when:
^ Vehicle speed = zero mph
^ Engine speed = idle
^ Fuel System in closed loop
^ Engine Temperature is between -8.25°C (17°F) and 50.25°C (122°F)
^ 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
The following conditions could result in a small leak:
^ Missing or leaking O-rings at fuel vapor line.
^ Cracked or damaged EVAP Canister.
^ Damaged source vacuum line, EVAP purge line, EVAP vent hose or fuel tank vapor line.
^ EVAP vent solenoid stuck open.
^ EVAP service port valve leak.