P0440

DESCRIPTION
The EVAP large leak test applies vacuum to the Evaporative Emission (EVAP) system and monitors vacuum decay. The Powertrain Control Module (PCM) monitors the Fuel Tank Pressure (FTP) sensor signal to determine the vacuum decay rate. At an appropriate time, the PCM turns the EVAP canister purge valve ON (open) and the EVAP vent valve ON (closed). This allows the engine to draw a vacuum on the EVAP system. At a calibrated time, or vacuum level, the PCM turns the purge valve OFF (closed), sealing the system, and monitors the FTP sensor input in order to determine EVAP system vacuum. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, DTC P0440 will set.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0452, or P0453 are not set.
^ The ignition voltage is between 10-18 volts.
^ The Barometric Pressure (BARO) is more than 75 kPa.
^ The fuel level is between 15-85 percent.
^ The Engine Coolant Temperature (ECT) is between 4-30°C (39-86°F).
^ The Intake Air Temperature (IAT) is between 4-30°C (39-86°F).
^ The start up ECT and IAT are within 9°C (16°F) of each other.
^ 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.
^ Use a scan tool in order to clear the MIL and the DTC.

DIAGNOSTIC AIDS
^ Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to set occurs. This may assist in diagnosing the condition.
^ Use the EVAP Pressure/Purge Diagnostic Station in order to pressurize the EVAP system to aid in locating intermittent leaks. Move all EVAP components while testing with the Ultrasonic Leak Detector.
^ 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. Service and Repair

TEST DESCRIPTION

Steps 1-9:

Steps 10-12:

Steps 13-18:

Steps 19-32:

The numbers below refer to the step numbers on the diagnostic table:
4. This test verifies that the EVAP purge valve is electrically functional.
5. This test verifies that the EVAP vent valve is electrically functional.
10. This test verifies that engine vacuum is present when the EVAP purge valve is open.
12. This test verifies that the FTP sensor is accurate. An EVAP FTP sensor that does not correctly respond to vacuum (or pressure) may cause this DTC to set