DTC P0442. Pontiac Vibe

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2004 🢒 Vibe - FWD 🢒 DTC 🢒 DTC P0442

System Description

When running the DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected diagnostic detects evaporative emission system leaks as small as 1.02 mm (0.040 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 pressure (FTP) sensor signal in order 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

•	DTCs P0450, P0451, P0452, and P0453 are not set.

•	The barometric pressure (BARO) indicates that the altitude is less than 2,400 meters (7,872 feet).

•	The battery voltage is at least 11 volts.

•	The fuel level is approximately 10-90 percent--no excess fuel slosh is indicated.

•	The engine coolant temperature (ECT) sensor and the intake air temperature (IAT) sensor are near the same temperature at engine start.

•	The ECT and the IAT are between 10°C (50°F) and 32°C (89°F) at engine start.

•	The engine has been operating for at least 50 minutes.

•	The vehicle is operated at steady speeds.

•	The EVAP canister purge valve has been open and the fuel tank pressure (FTP) sensor indicates a negative pressure in the fuel tank of at least -18 mm Hg (-9.63 inches H2O).

•	DTC P0442 runs once per drive cycle when the above conditions are met.

Conditions for Setting the DTC

Either of the fallowing conditions are present:

•	Condition 1--The FTP sensor determines that the EVAP system is unable to achieve a vacuum, indicating a large leak.

•	Condition 2--The EVAP system can achieve vacuum, but a vacuum decay that is 0.040 inch or more 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 0.020 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.

•	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 .

•	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.

•

The test for leaks with smoke is performed with the system subjected to positive pressure. The trouble code diagnostic tests for a leak with vacuum or negative pressure. Perform the Purge/Seal test with the scan tool in order to test for leaks using vacuum pressure. Refer to Purge/Seal Function in Service Bay Test . If the Purge/Seal test fails, inspect the EVAP system o-ring seals for failure. O-ring seals can provide a good seal with pressure applied in one direction, but leak when the pressure is applied in the opposite direction.

•	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 .

•	For intermittent conditions refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

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.

This test verifies that the EVAP purge solenoid is electrically functional.

This test verifies that the EVAP vent solenoid is electrically functional.

This test verifies that the EVAP pressure switching solenoid is electrically functional

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. The EVAP vent solenoid DOES NOT have to be turned ON in order to test for leaks. A one way check valve located in the vent port of the EVAP canister provides containment of smoke and pressure within the EVAP system.

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.

This step tests the functional operation of the EVAP pressure switching solenoid.

This step tests the functional operation of the EVAP vent solenoid.

This step tests the functional operation of the EVAP purge solenoid.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Install a scan tool.
Check for DTCs.

Is a DTC P0450, P0451, P0452, or P0453 present?

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

Review the Freeze Frame/Failure Records.
Diagnose the DTC captured in the Freeze Frame/Failure records first.

Is DTC P0442 captured in the Freeze Frame/Failure records?

Go to Step 4

Go to Diagnostic Trouble Code (DTC) List

Inspect the EVAP system for the following conditions:

•	A loose, missing, or damaged service port schrader valve

•	A loose, incorrect, missing, or damaged fuel fill cap

•	A damaged EVAP purge solenoid

Raise the vehicle on a hoist. Refer to Lifting and Jacking the Vehicle in General Information.
Inspect the EVAP system for the following conditions:

•	Any disconnected, improperly routed, kinked, or damaged EVAP pipes and hoses

•	A damaged EVAP vent solenoid or EVAP canister

Did you find and correct the condition?