GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 STS 🢒 Engine 🢒 Engine Controls - 4.6L (LH2) 🢒 DTC P0442

System Description

This diagnostic tests the evaporative emission (EVAP) system for a small leak when the key is turned OFF and the correct conditions are met.

Heat from the exhaust system is transferred into a vehicle fuel tank while the vehicle is operating. When the vehicle is turned OFF, a change in fuel tank vapor temperature occurs. In a sealed system this results in corresponding pressure changes in the fuel tank vapor space. This change is monitored by the control module using the fuel tank pressure (FTP) sensor input. The control module then makes a judgement on the integrity of the system. With a 0.51 millimeter (0.02 inches) leak in the system, the amount of pressure change observed is significantly less than that of a sealed system.

If the control module detects a pressure change less than a calibrated amount, DTC P0442 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

P0442 EVAP System Small Leak Detected

Conditions for Running the DTC
    • DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0068, P0101, P0102, P0103, P0111, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0151, P0152, P0153, P0154, P0155, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0221, P0222, P0223, P0261, P0262, P0264, P0265, P0268, P0270, P0271, P0273, P0274, P0276, P0277, P0279, P0280, P0282, P0283, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0313, P0443, P0446, P0449, P0452, P0453, P0454, P0458, P0459, P0496, P0498, P0499, P0500, P0722, P0723, P1111, P1112, P1114, P1115, P1791, P1795, P2100, P2101, P2108, P2119, P2122, P2123, P2127, P2128, P2135, P2138, P2234 are not set.
    • The diagnostic runs once with 10-hour minimum between tests after a fail.
    • DTC P0455 must run and PASS.
    • The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).
    • The start-up engine coolant temperature (ECT) is less than 30°C (86°F).
    • The start-up IAT and ECT are within 8°C (15°F).
    • The barometric pressure (BARO) is more than 74 kPa.
    • The ambient air temperature is between 2-32°C (36-90°F).
    • The engine run time minimum is 10 minutes.
    • The odometer displays more than 16 kilometers (10 miles).
    • The vehicle has traveled more than 5 kilometers (3 miles) this trip.
    • The ECT is more than 70°C (158°F).
    • The fuel level is between 15-85 percent.
    • The ignition is OFF.

Conditions for Setting the DTC

The control module detects a pressure change that is less than a calibrated amount.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the 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
    • A condition may exist where a leak in the EVAP system only exists under a vacuum condition. By using the scan tool PURGE/SEAL function to create a vacuum, seal the system and observe the FTP parameter for vacuum decay. This type of leak may be detected.
    • To help locate intermittent leaks, 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.
    • 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 intermittent conditions, refer to Intermittent Conditions .

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

    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 (0.02 in) test orifice on the bottom-front of the J 41413-200 Evaporative Emission System Tester (EEST).
  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 J 41415-40 or GE-41415-50 Fuel Tank Cap Adapter to the fuel fill pipe.
  6. Remove the nitrogen/smoke hose from the test orifice and install the hose onto the J 41415-40 or GE-41415-50 .
  7. Turn ON the ignition, with the engine OFF.
  8. Command the evaporative emission (EVAP) vent solenoid closed with a scan tool.
  9. Use the remote switch to introduce nitrogen and fill the EVAP system until the floating stabilizes.
  10. Compare the flow meter stable floating indicator position to the red flag.

is the floating indicator below the red flag?

Go to Diagnostic Aids

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 power supply clips to a known good 12-volt source.
  3. Install the J 41415-40 or GE-41415-50 to the fuel fill pipe.
  4. Connect the J 41413-200 nitrogen/smoke supply hose to the J 41415-40 or GE-41415-50 .
  5. Turn ON the ignition, with the engine OFF.
  6. Command the EVAP vent solenoid 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 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. 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 J 41415-40 or 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 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 (0.02 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 J 41415-40 or GE-41415-50 to the fuel fill pipe.
  6. Remove the nitrogen/smoke hose from the test orifice and install the hose onto the J 41415-40 or GE-41415-50 .
  7. Turn ON the ignition, with the engine OFF.
  8. Command the EVAP vent solenoid valve closed with a scan tool.
  9. Use the remote switch to introduce nitrogen and fill the EVAP system until the floating indicator stabilizes.
  10. Compare the flow meter 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

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