P0440

CIRCUIT DESCRIPTION
The evaporative emission (EVAP) system large leak test applies vacuum to the EVAP system and monitors the rate of vacuum decay. The control module monitors the fuel tank pressure (FTP) sensor in order to determine the rate of vacuum decay. At an appropriate time, the control module turns the EVAP canister purge valve ON (open) and the EVAP canister vent valve ON (closed). This allows the engine to draw a vacuum on the system. At a calibrated time or vacuum level, the control module turns the purge valve OFF (closed), and tests the system vacuum. If the system is unable to achieve the calibrated vacuum level, the PCM will set DTC P0440.

CONDITIONS FOR RUNNING THE DTC
^ DTC P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0443, P0449, P0452, P0453, P1111, P1112, P1114, P1115, P1121, and P1122 are not active.
^ The system voltage is between 10-18 volts.
^ The startup engine coolant temperature (ECT) is between than 4-30°C (39-86°F).
^ The startup intake air temperature (IAT) is between and 4-30°C (39-86°F).
^ The ECT and IAT are within 9°C (16°F) of each other.
^ The fuel tank level is between 15-85 percent.
^ The barometric pressure (BARO) is more than 75 kPa.
^ The vehicle speed sensor (VSS) is less than 121 km/h (75 mph).

CONDITIONS FOR SETTING THE DTC
The EVAP system is not able to achieve or maintain vacuum during the diagnostic test.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
^ Use the EVAP pressure/purge diagnostic station in order to pressurize the EVAP system to aid in locating intermittent leaks.
^ A temporary blockage in the EVAP canister purge valve, purge pipe or EVAP canister could cause an intermittent condition. To repair a blockage in the EVAP system, refer to Evaporative Emission (EVAP) System Cleaning.

TEST DESCRIPTION

Steps 1-8:

Steps 9-14:

Steps 15-20:

The numbers below refer to the step numbers on the diagnostic table.
4. This step verifies that a failure condition is active.
5. This step verifies if a leak is present.
6. This step verifies proper operation of the fuel tank pressure (FTP) sensor.
10. This step tests the EVAP canister purge valve for a restriction or blockage.
19. This step verifies that repairs are complete and that no other condition is present.