GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2005 🢒 LaCrosse 🢒 Restraints 🢒 SIR 🢒 DTC P0442

System Description

This diagnostic tests the evaporative emission (EVAP) system for a small leak. The diagnostic runs when the ignition is in the OFF position, and the correct conditions are met. While the engine is operating, there are sources of heat transferred into the fuel tank from the following:

    • Exhaust heat
    • Engine heat
    • Ambient temperature

When the engine is stopped and the ignition is in the OFF position a change in the fuel tank vapor temperature occurs. This results in a change in the pressure of the fuel tank vapor space. This change in pressure is monitored by the control module, using the fuel tank pressure (FTP) sensor input. The EVAP diagnostic detects leaks as small as 0.51 mm (0.020 in). If the control module detects a change in the fuel tank vacuum/pressure less than a calibrated amount, this DTC sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected

Conditions for Running the DTC

Important: The following conditions must be met prior to the ignition OFF test.

    • DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0125, P0128, P0443, P0446, P0449, P0451, P0452, P0453, P0458, P0459, P0496, P0498, P0499, P0560, P0562, P0563, P0700, P2228, and P2229 are not set.
    • The ignition 1 voltage is more than 11 volts.
    • A refueling event is not detected.
    • The fuel volatility is not excessive.
    • The ambient air temperature is between 2-32°C (36-90°F).
    • The start-up intake air temperature (IAT) is between 2-32°C (36-90°F).
    • The start-up engine coolant temperature (ECT) is less than 40°C (104°F) and within 10°C (18°F) of the IAT.
    • The ECT is more than 74°C (165°F) at engine OFF.
    • The barometric pressure (BARO) is more than 68 kPa.
    • The fuel level is between 12-88 percent.
    • The engine run time is more than 10 minutes.
    • The vehicle traveled more than 8 km (5 miles) with vehicle speed above 3.2 km/h (2 mph).
    • The vehicle odometer displays more than 20 km (12.5 miles).
    • DTC P0442 runs once per ignition OFF cycle when the above conditions are met prior to engine shut-down.

Conditions for Setting the DTC

The control module detects approximately 8 vacuum/pressure changes significantly less than a calibrated amount.

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 MIL after approximately 6 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 an intermittent leak, use the J 41413-200 Evaporative Emission 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.
    • To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT .
    • For an intermittent condition, refer to Intermittent Conditions .

Test Description

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

  1. Introducing smoke in 15 second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.

  2. This step verifies that repairs are complete and that no other condition is present.

P0442 Evaporative Emission (EVAP) System Small Leak Detected

Step

Action

Yes

No

Schematic Reference: Evaporative Emissions Hose Routing Diagram

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2
  1. Inspect the evaporative emission (EVAP) system for the following conditions:
    2. • Loose, missing, or damaged service port dust cap and/or schrader valve
    • Loose, incorrect, missing, or damaged fuel fill cap
    • A damaged EVAP purge solenoid
  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 hose
    • A damaged EVAP vent valve or EVAP canister

Did you find and correct the condition?

Go to Step 5

Go to Step 3

3

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 Evaporative Emission System Tester (EEST) power supply clips to a known good 12-volt source.
  3. Install the GE-41415-50 Fuel Tank Cap Adapter to the fuel fill pipe.
  4. Connect the J 41413-200 nitrogen/smoke supply hose to the GE-41415-50 .
  5. Turn ON the ignition, with the engine OFF.

    6. Important: The DTCs may need to be cleared if the output control does not operate.

  6. Command the EVAP vent valve closed with a scan tool.
  7. Turn the nitrogen/smoke valve on the J 41413-200 control panel to SMOKE.
  8. Use the remote switch on the J 41413-200 to introduce smoke into the EVAP system.
  9. Use the J 41413-VLV EVAP Port Vent Fitting tool 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. Inspect the entire EVAP system for exiting smoke with the J 41413-SPT High Intensity White Light.
  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 5

Go to Step 4

4
  1. Disconnect the GE-41415-50 from the fuel fill pipe.
  2. Install the fuel fill cap to the fuel fill pipe.
  3. Connect the J 41413-200 nitrogen/smoke supply hose to the EVAP service port.
  4. Use the remote switch on the J 41413-200 to introduce smoke into the EVAP system.
  5. Inspect the entire EVAP system for exiting smoke with the J 41413-SPT .
  6. 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 5

Go to Diagnostic Aids

5

Important: Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize.

  1. Turn the nitrogen/smoke valve to nitrogen.
  2. Connect the nitrogen/smoke hose to the 0.5 mm (0.020 in) test orifice on the bottom-front of the J 41413-200 .
  3. Use the remote switch to activate the J 41413-200 .
  4. Align the red flag on the flow meter with the floating indicator. Use the remote switch to de-activate the J 41413-200 .
  5. Install the GE-41415-50 to the fuel fill pipe.
  6. Remove the nitrogen/smoke hose from the test orifice and install the hose onto the GE-41415-50 .
  7. Turn ON the ignition, with the engine OFF.

    8. Important: The DTCs may need to be cleared if the output control does not operate.

  8. Command the EVAP vent solenoid closed with a scan tool.
  9. Use the remote switch on the J 41413-200 to introduce nitrogen and fill the EVAP system until the floating indicator stabilizes.
  10. Compare the flow meter's stable floating indicator position to the red flag.

Is the floating indicator below the red flag?

Go to Step 6

Go to Step 2

6
  1. Clear the DTCs with a scan tool.
  2. Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK