GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2004 🢒 GTO 🢒 DTC 🢒 DTC P0442

Circuit Description

The EVAP small leak test applies vacuum to the EVAP system and monitors vacuum decay. The control module monitors the fuel tank pressure sensor signal to determine the vacuum decay rate. At an appropriate time, the EVAP canister purge valve and the EVAP vent valve are turned ON. This allows the engine to draw vacuum on the EVAP system. After the desired vacuum level has been achieved, the EVAP purge valve is turned OFF, sealing the system. A leak is detected by monitoring for a decrease in the vacuum level during a given time period. If the system detects a leak larger than a calibrated amount, DTC P0442 will set.

DTC Descriptors

This diagnostic procedure supports the following DTC.

DTC P0442 Evaporative Emissions (EVAP) Small Leak Detected

Conditions for Running the DTC
    • DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0157, P0158, P0160, P0171, P0172, P0174, P0175, P0452, P0453, P0502, P0503, P0641, P0651, P1111, P1112, P1114, P1115, P1121, P1122, P1133, P1134, P1153, and P1154 are not set.
    • The system voltage is between 10-18 volts.
    • The startup ECT is between 4-30°C (39-86°F).
    • The startup IAT is between 4-30°C (39-86°F).
    • The start up ECT and IAT are within 8°C (14°F) of each other.
    • The fuel tank level is between 15-85 percent.
    • The startup barometric pressure (BARO) is more than 75 kPa.
    • The vehicle speed sensor (VSS) is less than 90 km/h (75 mph).
    • DTC P0442 runs once per ignition cycle when the above conditions are met.

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 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.
    • Clear the MIL and the DTC with a scan tool.

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. Introducing smoke in 15 second intervals will allow less pressure into the EVAP system. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.

Test Description

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

  1. This step verifies that a failure condition is active.

    2.

  2. This step verifies that repairs are complete and that other conditions are not present.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

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

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Does the scan tool indicate DTC P0443, P0449, P0452, or P0453 are also set?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3
  1. Inspect the EVAP system for the following conditions:
    2. • Loose, missing, or damaged service port Schrader valve
    • Loose, incorrect, missing, or damaged fuel fill cap
    • A damaged EVAP canister purge valve.
  2. Raise the vehicle on a hoist. Refer to Lifting and Jacking the Vehicle in General Information.
  3. Inspect the EVAP system for the following conditions:
    4. • Disconnected, improperly routed, kinked or damaged EVAP pipes and hoses
    • A damaged EVAP canister vent valve or EVAP canister

Did you find and correct the condition?

--

Go to Step 6

Go to Step 4

4

  1. With a scan tool, capture and record the failure record and clear the DTCs.
  2. Perform the Service Bay Test. Refer to Service Bay Test .

Does the scan tool indicate that the service bay test passed?

--

Go to Diagnostic Aids

Go to Step 5

5

Important: Ensure that the vehicle underbody temperature is similar to the ambient temperature and allow the surrounding air to stabilize before starting the diagnostic procedure. System flow will be less with higher temperatures.

  1. Turn OFF the ignition.
  2. Connect the J 41413-200 power supply clips to a known good 12-volt source.
  3. Install the GE-41415-50 Interrupted Thread Fuel Tank Cap Adapter to the fuel fill pipe.
  4. Connect the J 41413-200 nitrogen/smoke supply hose and vehicle fuel fill cap to the GE-41415-50 .
  5. Turn ON the ignition, with the engine OFF
  6. Command the EVAP canister vent solenoid valve closed with a scan tool. Refer to Scan Tool Output Controls .
  7. Turn the nitrogen/smoke valve on the J 41413-200 control panel to SMOKE.
  8. Use the remote switch to introduce smoke into the EVAP system.
  9. Use the J 41413-VLV EVAP Service Port Vent Fitting to open the EVAP service port.
  10. Remove the J 41413-VLV once smoke is observed.
  11. Continue to introduce smoke into the EVAP system for an additional 60 seconds.
  12. Use the J 41413-SPT High Intensity White Light in order to inspect for exiting smoke in the following locations:
    13. • The EVAP system purge lines and hoses.
    • The EVAP vapor lines and hoses.
    • The EVAP vent lines and hoses.
    • The fuel fill pipe and hose, and the fuel fill cap.
    • The EVAP canister. Refer to Evaporative Emission Canister Replacement .
    • The EVAP canister vent valve. Refer to Evaporative Emission Canister Vent Solenoid Valve Replacement .
    • The EVAP canister purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
    • The fuel sender assembly and/or seal. Refer to Fuel Sender Assembly Replacement .
    • The fuel tank pressure (FTP) sensor seal. Refer to Fuel Tank Pressure Sensor Replacement .
    • The fuel tank assembly--Inspect the following components:
       - The fill limiter vent valve
       - The pressure relief valve
       - The rollover valves
  13. Continue to introduce smoke at 15 second intervals until the leak source has been located

Did you locate and repair a leak source?

--

Go to Step 6

Go to Diagnostic Aids

6

Perform the Service Bay Test. Refer to Service Bay Test .

Does the scan tool indicate that the service bay test passed?

--

Go to Step 7

Go to Step 2

7

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK