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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Cobalt 🢒 Engine 🢒 Engine Controls - 2.0L 🢒 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 and the EVAP system is sealed, a change in the fuel tank vapor temperature occurs, which results in corresponding pressure changes in the fuel tank vapor space. This change is monitored by the control module using the fuel tank pressure sensor input. The control module then makes a judgement on the integrity of the system. With a 0.51 mm (0.020 in) 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:

DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected

Conditions for Running the DTC

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

    • DTCs P0095, P0096, P0097, P0098, P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0128, P0336, P0443, P0446, P0452, P0453, P0455, P0461, P0462, P0463, P0464, P0496, P0502, P0503, P2610 are not set.
    • The diagnostic runs once after a cold start drive cycle.
    • 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 vehicle has traveled more than 5 km (3.1 mi) this trip.
    • The ECT is more than 70°C (158°F).
    • The fuel level is between 15-85 percent.
    • The ignition is OFF.
    • One test occurs at ignition OFF after a drive cycle and may require up to 45 minutes to complete. No more than 2 tests per day are allowed. To report a fail, 5-12 tests must be completed.

Conditions for Setting the DTC

The control module detects a pressure change that is less than a calibrated amount within 45 minutes after ignition OFF when the above conditions have been met.

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
    • A leak in the EVAP system can be verified by the use of the flow meter on the J 41413-200 Evaporative Emissions System Tester (EEST). Refer to J 41413-200 operation manual for flow meter use.
    • To help locate intermittent leaks, use the J 41413-200 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 .
    • 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.
    • For intermittent conditions, refer to Intermittent Conditions .
    • 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.

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step verifies that repairs are complete.

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

2

Important: Refer to J 41413-200 Evaporative Emissions System Tester (EEST) operation manual for detailed instructions.

  1. Using the GE-41415-50 Fuel Tank Cap Adapter, connect the J 41413-200 to the vehicle's filler neck.
  2. Use the flow meter on the J 41413-200 and the GE-41415-50 to determine if there is a leak greater than 0.51 mm (0.020 in) in the evaporative emission (EVAP) system.
  3. 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: Refer to J 41413-200 operation manual for detailed instructions.

  1. Turn ON the ignition, with the engine OFF with the J 41413-200 still connected to the filler neck.
  2. Seal the system and apply smoke to the system until smoke is visible at J 41413-VLV EVAP Service Port Vent Fitting. Continue to apply smoke for an additional 60 seconds.
  3. Inspect the entire EVAP system for exiting smoke with the J 41413-SPT High Intensity White Light.
  4. 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 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. Use the flow meter on the J 41413-200 to determine if there is a leak greater than 0.51 mm (0.020 in) in the EVAP system.
  2. 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

Go to Step 7

7

Important: The malfunction indicator lamp (MIL) may remain ON after the repair unless the DTCs are cleared.

Clear the DTCs with a scan tool.

Did you complete the action?

System OK

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