P0442

SYSTEM DESCRIPTION
When running the DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected diagnostic detects evaporative emission system leaks as small as 0.5mm (0.020) inch. The powertrain control module (PCM) will command the EVAP vent valve ON, CLOSED, and the purge valve and the vacuum pressure switching valve ON, OPEN, with the engine running. This allows engine vacuum into the EVAP system. The PCM then commands the purge valve OFF, CLOSED, sealing the system. The PCM then monitors the fuel tank vapor pressure sensors signal to determine if there is vacuum decay. A rise or increase just above normal pressure indicates there is a small leak in the evaporative emission system. If the PCM detects the vacuum level was not achieved and vacuum decay was within a specified value a DTC P0442 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 valve 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 can achieve vacuum, but a vacuum decay is detected 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
- The EVAP control system is required to detect evaporative emission fuel system leaks as small as 0.5mm (0.020) inch, between the fuel fill cap, and the purge solenoid.
- 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.
- 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.
- To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT.
- 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
- Reviewing the Freeze Frame Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

TEST DESCRIPTION

Steps 1-3:

Step 4:

Step 5:

Steps 6-9:

Steps 10-11:

The numbers below refer to the step numbers on the diagnostic table.
3. This step verifies that the DTC P0442 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. 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.
7. 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.