P0440

Circuit Description
The PCM tests the EVAP system for the following conditions:
^ Large and small leaks
^ Excess vacuum
^ Purge flow during non-commanded conditions
^ Fuel Level and Fuel Pressure sensor faults
^ EVAP Purge and Vent Valve faults
The PCM monitors the Fuel Tank Pressure sensor in order to determine the level of vacuum/pressure in the EVAP system. The PCM commands both the EVAP Purge Solenoid and the EVAP Vent Valve ON when the Conditions for Running the DTC are met in order to apply an engine vacuum to the EVAP system. The PCM commands the EVAP Purge Solenoid OFF once the system has reached a predetermined level of vacuum. This test confirms if a vacuum can be achieved in the EVAP system. Failure to develop a vacuum may be caused by a large leak or a restriction. This DTC sets after twice failing the above test.

Conditions for Running the DTC
^ DTCs P0107, P0108, P0112, P0113, P0121, P0122, P0123, P0131-P0161, P0420, P0430, P0500, P0502, P0503, P0562, P0563, P1111, P1112, not set.
^ The ignition voltage is between 10.0 volts and 18.0 volts.
^ The barometric pressure is greater than 75 kPa.
^ The fuel level is between 15% and 85% of full capacity.
^ The engine coolant temperature is between 4°C (39°F) and 30°C (86°F).
^ The intake air temperature is between 4°C (39°F) and 30°C (86°F).
^ The start up engine coolant and intake air temperatures are within 9°C (16°F) of each other.

Conditions for Setting the DTC
The EVAP system cannot develop a vacuum greater than a predetermined value.

Important: This DTC does NOT report a first failed test. A first fail of this DTC will have a scan tool status as Not Run. Use the scan tool data display parameter of EVAP Test Result to determine if this DTC has failed or passed for this ignition cycle.

Action Taken When the DTC Sets
^ The PCM illuminates the Malfunction Indicator Lamp on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure records.

Conditions for Clearing the MIL/DTC
^ The PCM turns the MIL OFF after three consecutive ignition cycles that the diagnostic runs and does not fail.
^ A last test failed (current DTC) clears when the diagnostic runs and does not fail.
^ A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
^ Use a scan tool in order to clear the MIL/DTC.

Diagnostic Aids

Important:
^ Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
^ An accurate indication of fuel level is required for the PCM to properly Pass or Fail this DTC. Always diagnose fuel level sensor DTC's before performing this DTC's diagnostic table. Always inspect for fuel level sensor DTC's stored as History.
^ The Service Bay Test may have to be performed in cold ambient air temperatures when the vehicle is running a winter grade fuel. The scan tool displays a message when the service bay test does not run.
^ Inspect for charcoal release from the vapor canister.

Conditions for Running the Service Bay Test
^ The battery voltage is between 10.5 and 17.5 volts.
^ The fuel level is between 15% and 85% of the full capacity.
^ The engine temperature is between 3.5°C (38°F) and 35°C (95°F).

Perform a physical inspection of the EVAP system. Inspect for the following conditions:
^ A loose, missing, defective, or incorrect fuel tank cap
^ Incorrectly routed or defective EVAP system vacuum and vapor lines
^ A malfunctioning or damaged vapor canister
^ Inspect for charcoal release from the vapor canister.
The vacuum and pressure in the EVAP system is measured in inches of H2O (water). Most gauges measure vacuum in inches of Hg (mercury) and pressure in psi (pounds per square inch). The table illustrates how the values compare.

Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
3. It may be necessary to partially lower the fuel tank to inspect the upper portion of the tank and the EVAP line connections.
4. An intermittent leak or restriction is indicated if the vehicle passes the Service Bay Test. A fuel tank cap that is loose or off causes this DTC to set. If the Service Bay Test can not be run, proceed to Step 5.If a fault is not currently present the diagnostic table steps will return you to Step 3.
12. Refer to the information supplied with the EVAP pressure/purge diagnostic cart on proper setup and adjustment procedures.
This step tests for a leak at the top of the fuel tank, at the fuel filler hose, and the fuel cap. Place the ultrasonic leak detector in these areas.
13. With pressure applied it may be necessary to disconnect the EVAP lines at the components to verify that a line or component is not restricted. A restriction would prevent a vacuum (or the Step 10 test pressure) from forming in the fuel tank.
19. A Fuel Tank Pressure sensor that does not correctly respond to pressure (or vacuum) causes this DTC to set.
The Fuel Tank Pressure sensor range is from 7.5 in. H2O of pressure to -17.5 in. H2O of pressure (vacuum).
In order to test the Fuel Tank Pressure sensor for vacuum response, command the EVAP Purge Solenoid Valve ON with the engine running and quickly SEAL the system. Leaving the EVAP Purge Solenoid Valve ON for a longer period of time allows a greater level of vacuum to develop.