P0440

SYSTEM DESCRIPTION
The DTC P0440 Evaporative Emission (EVAP) System diagnostic evaluates the operation of the EVAP control system. The powertrain control module (PCM) will command the EVAP vent valve ON, CLOSED, and the purge solenoid and the EVAP pressure switching solenoid ON, OPEN, with the engine running. This allows engine vacuum into the EVAP system. The PCM then commands the purge solenoid OFF, CLOSED, sealing the system. The PCM then monitors the fuel tank vapor pressure sensor signal in order to determine if there is vacuum decay. A rise or rapid increase in pressure indicates there is a large leak in the evaporative emission system. If the PCM detects the vacuum level was not achieved and vacuum decay was evident a DTC P0440 will set.

CONDITIONS FOR RUNNING THE DTC
- The barometric pressure (BARO) is more than 75 kPa.
- The fuel level is between 25-75 percent.
- The ECT sensor and the intake air temperature (IAT) sensor are near the same temperature at engine start.
- The ECT sensor is at least 74°C (165°F) after engine warm up.
- The vehicle has been driven for at least 20 minutes.
- The EVAP canister purge solenoid has been open and the fuel tank pressure (FTP) sensor indicates a negative pressure in the fuel tank.

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

ACTION TAKEN WHEN THE DTC SETS
- The PCM illuminates the malfunction indicator lamp (MIL) after 2 consecutive ignition cycles in which the diagnostic runs with the fault active.
- The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

CONDITIONS FOR CLEARING THE MIL/DTC
- The PCM turns OFF the MIL on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
- A DTC will clear after 40 consecutive warm-up cycles have occurred without a fault.
- A DTC can be cleared by using the scan tool Clear Information function.

DIAGNOSTIC AIDS
- To help locate intermittent leaks, use the J 41413-200 Evaporative Emissions System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. In order to improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT light.
- A temporary blockage in the EVAP purge solenoid, purge pipe or EVAP canister could cause an intermittent condition. Inspect and repair any restriction in the EVAP system.
- Operating the vehicle in Check Mode will increase the ability of the powertrain control (PCM) module to detect engine control system malfunctions. Refer to Check Mode in Service Bay Test. Component Tests and General Diagnostics
- For intermittent conditions refer to Intermittent Conditions. Intermittent Conditions
- If the DTC cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.

TEST DESCRIPTION

Steps 1-3:

Steps 4-7:

Steps 8-10:

Steps 11-12:

Step 13:

Step 14:

Steps 15-20:

Steps 21-26:

Steps 27-32:

Steps 33-40:

Steps 41-44:

Step 45:

The numbers below refer to the step numbers on the diagnostic table.
3. This test verifies that the DTC P0440 is captured in the freeze frame/failure record list. When multiple EVAP system DTCs are set, the DTC stored in the freeze frame/failure record is the best diagnostic starting point.
5. This test verifies that the EVAP purge solenoid is electrically functional.
6. This test verifies that the EVAP vent solenoid is electrically functional.
7. This test verifies that the EVAP pressure switching solenoid is electrically functional.
14. The fuel filler pipe has two vent lines that allow for recirculation of fuel vapors between the fuel filler pipe and the fuel tank. Because of these vent lines the EEST can be connected to the EVAP service port for leak detection. Waiting until smoke is seen before plugging the EVAP canister drain hose speeds up the filling of the canister with smoke. Introducing smoke in between 60 second intervals of Nitrogen will speed up the filling of smoke in the fuel tank and filler pipe vapor space. This occurs because the pressure at which Nitrogen gas is applied is greater than the pressure at which smoke is introduced. The Nitrogen gas pushes the smoke that was just introduced through the canister and into the fuel tank.
15. This test verifies that the fuel tank pressure (FTP) sensor is accurate. An FTP sensor that does not correctly respond to vacuum, or pressure may cause this DTC to set.