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

System Description

This DTC tests the evaporative emission (EVAP) system for a small leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the vacuum decay rate. At an appropriate time, the control module turns the EVAP canister purge solenoid valve ON and the EVAP vent solenoid valve ON. This allows the engine to draw a vacuum on the EVAP system. At a calibrated time, or vacuum level, the control module turns the EVAP canister purge solenoid valve OFF, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum decay. If the control module detects a leak larger than a calibrated amount, this DTC sets.

The following table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP canister purge and vent solenoid valves.

Control Module Command

EVAP Canister Purge Solenoid Valve

EVAP Canister Vent Solenoid Valve

ON

Open

Closed

OFF

Closed

Open

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected

Conditions for Running the DTC
    • Before the powertrain control module (PCM) can report DTC P0442 failed, DTCs P0496 and P0455 must run and pass.
    • DTCs P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0443, P0449, P0452, P0453, P0502, P1106, P1107, P1111, P1112, P1114, P1115, P1121, P1122 are not set.
    • The ignition voltage is between 10-18 volts.
    • The barometric pressure (BARO) is more than 74 kPa.
    • The fuel level is between 15-85 percent.
    • The engine coolant temperature (ECT) is between 4-30°C (39-86°F).
    • The intake air temperature (IAT) is between 4-30°C (39-86°F).
    • The start up ECT and IAT are within 9°C (16°F) of each other.
    • The vehicle speed sensor (VSS) is less than 129 km/h (80 mph).
    • DTC P0442 runs once per cold start 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.
    • 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 .

Test Description

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

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

    2.

  2. 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.

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

Step

Action

Values

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

2

  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Perform the Service Bay Test. Refer to Service Bay Test .

Does the scan tool display Service Bay Test passed?

--

Go to Diagnostic Aids

Go to Step 3

3
  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 valve
  2. Raise the vehicle on a hoist. Refer to Lifting and Jacking the Vehicle .
  3. Inspect the EVAP system for the following conditions:
    4. • Disconnected, improperly routed, kinked, or damaged EVAP pipes and hose
    • A damaged EVAP vent solenoid valve or EVAP canister

Did you find and correct the condition?

--

Go to Step 6

Go to Step 4

4

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 Emissions System Tester (EEST) power supply clips to a known good 12-volt source.
  3. Install the J 41415-40 Fuel Tank Cap Adapter to the fuel fill pipe.
  4. Connect the fuel fill cap to the J 41415-40 .
  5. Connect the J 41413-200 nitrogen/smoke supply hose to the J 41415-40 .
  6. Turn ON the ignition with the engine OFF.
  7. Command the EVAP vent solenoid valve closed with a scan tool.
  8. Turn the nitrogen/smoke valve on the J 41413-200 control panel to SMOKE.
  9. Use the remote switch to introduce smoke into the EVAP system.
  10. Use the J 41413-VLV EVAP Service Port Vent Fitting to open the EVAP service port.
  11. Remove the J 41413-VLV once smoke is observed.
  12. Continue to introduce smoke into the EVAP system for an additional 60 seconds.
  13. Inspect the entire EVAP system for exiting smoke with the J 41413-SPT High Intensity White Light.
  14. 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 Step 5

5
  1. Disconnect the J 41415-40 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 6

Go to Diagnostic Aids

6

Perform the Service Bay Test .

Does the scan tool indicate that the Service Bay Test passed?

--

Go to Step 7

Go to Step 3

7

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

System OK