GM Service Manual Online
For 1990-2009 cars only

System Description

The DTC P0441 Evaporative Emission (EVAP) System No Flow During Purge diagnostic monitors the changes in the vacuum pressure in the fuel tank. The powertrain control module (PCM) will command the EVAP vent valve ON, CLOSED, and the vacuum pressure switching valve ON, OPEN, with the engine running. This allows engine vacuum into the entire EVAP system. The PCM continues to operate the purge valve until the vacuum has reached a specified limit, at which time the PCM commands the purge valve OFF, CLOSED. If the PCM detects the vacuum level was not achieved, or the vacuum level increased beyond the specified limit, a DTC P0441 will set.

Conditions for Running the DTC

    • The barometric pressure (BARO) is more than 75 kPa.
    • The fuel level is between 25 and 75  percent.
    • The ECT sensor and the intake air temperature (IAT) sensor are near the same temperature at engine start.
    • The ECT sensor is at least 74°C (165°F) after engine warm up.

Conditions for Setting the DTC

The pressure indicated in the EVAP canister and the fuel tank does not drop when the EVAP canister purge valve is ON.

OR:

The pressure indicated in the EVAP canister remains very low when compared to atmospheric pressure when the EVAP canister purge solenoid valve is OFF.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL) after 2 consecutive ignition cycles in which the diagnostic runs with the fault active.
    • The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC

    • The PCM turns OFF the MIL on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
    • A DTC will clear after 40 consecutive warm-up cycles have occurred without a fault.
    • A DTC can be cleared by using the scan tool Clear Information function.

Diagnostic Aids

    • If DTC P0441 is the only EVAP DTC set, the most likely cause is an inoperable EVAP canister purge valve. Inspect the EVAP canister purge valve carefully for faulty connections and erratic operation.
    • An intermittent malfunction may be caused by a fault in any of the EVAP solenoid electrical circuits. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .
    • If the DTC cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.
    • Operating the vehicle in Check Mode will increase the ability of the powertrain control (PCM) module to detect engine control system malfunctions. Refer to Check Mode in Service Bay Test

Test Description

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

  1. This step verifies the electrical operation of the EVAP canister purge solenoid.

  2. This step tests the function of the EVAP canister purge solenoid.

  3. This step uses the EVAP Purge/Seal function to test for the correct operation of the EVAP canister vent solenoid, the pressure switching solenoid, and the purge solenoid. Using the EVAP Purge/Seal function also tests for leaks by allowing the technician to seal the system and monitor the FTP sensor.

  4. This step tests for a blockage or restriction in the EVAP canister vent valve and hoses. If the vacuum does not drop to less than -18.68 mm Hg (-10.0 inches H2O) after 30 seconds, there is a faulty condition in the EVAP vent system. The EVAP vent portion of the EVAP control system is diagnosed in DTC P0446.

  5. This step uses the EVAP Purge/Seal function to test for the correct operation of the EVAP canister vent solenoid, the pressure switching solenoid, and the purge solenoid. Using the EVAP Purge/Seal function also tests for leaks by allowing the technician to seal the system and monitor the FTP sensor.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics and Evaporative Emissions Hose Routing Diagram

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

Install a scan tool and check for DTCs.

Is a DTC P0450, P0451, P0452, or P0453 present?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3

  1. Review the Freeze Frame/Failure Records.
  2. Diagnose the DTC captured in the Freeze Frame/Failure records first.

Is DTC P0441 captured in the Freeze Frame/Failure records?

--

Go to Step 4

Go to Diagnostic Trouble Code (DTC) List

4

Command the EVAP purge solenoid ON and OFF with the scan tool. Refer to Scan Tool Output Controls .

Do you hear or feel a click as the EVAP purge solenoid is commanded ON and OFF?

--

Go to Step 5

Go to Step 10

5

  1. Remove the purge line from the EVAP purge solenoid.
  2. Connect a vacuum gage to the EVAP purge solenoid purge port.
  3. Start the engine.

Does the vacuum gage indicate a vacuum being applied?

--

Go to Step 18

Go to Step 6

6

With the engine running command the purge valve ON, OPEN.

Does the vacuum gage indicate a vacuum being applied?

--

Go to Step 7

Go to Step 17

7

  1. Reinstall the EVAP purge line to the purge solenoid.
  2. Remove the fuel fill cap in order to release any pressure inside the fuel tank.
  3. Re install the fuel fill cap.
  4. Turn ON the ignition, with the engine OFF.
  5. Observe the FTP sensor parameter on the scan tool.

Is the FTP sensor within the specified range?

0.0-0.99 mm Hg (0.0-0.5 in H2O)

Go to Step 8

Go to Step 15

8

  1. Start the engine.
  2. Select the EVAP Purge/Seal function on the scan tool. Refer to Service Bay Test .
  3. Command the EVAP Purge/Seal function ON.

Does the FTP sensor indicate a reading of at least the first specified value for as long as the second specified value?

-28.20 mm Hg (-15.10 in H2O)

2 minutes

Go to Step 9

Go to Step 22

9

  1. Repeat the EVAP Purge/Seal test exactly as detailed below.
  2. Command the EVAP Purge /Seal function ON.
  3. Monitor the FTP sensor with the scan tool for the first specified value for the start of the test.
  4. Continue to observe the FTP sensor for 30 seconds after the purge/seal test is complete.

Did the FTP sensor indicate that the vacuum dropped to less than the second specified value in the 30 seconds after the test was complete?

-28.20 mm Hg (-15.10 in H2O)

-18.68 mm Hg (-10 in H2O)

Go to Diagnostic Aids

Go to DTC P0446

10

  1. Disconnect the EVAP purge solenoid.
  2. Turn ON the ignition, with the engine OFF.
  3. Connect a test lamp between the ignition positive voltage circuit of the EVAP purge solenoid and a known good ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 11

Go to Step 13

11

  1. Connect a test lamp between the ignition positive voltage circuit of the EVAP purge solenoid and the control circuit of the EVAP purge solenoid. Refer to Circuit Testing in Wiring Systems.
  2. Command the EVAP purge solenoid ON with a scan tool.

Does the test lamp illuminate when the EVAP purge solenoid is commanded ON and turn OFF when the EVAP purge solenoid is commanded OFF?

--

Go to Step 14

Go to Step 12

12

Test the control circuit of the EVAP purge solenoid for an open, a short to voltage, or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 16

13

  1. Repair the open or short to ground in the ignition positive voltage circuit of the EVAP purge solenoid. Refer to Wiring Repairs in Wiring Systems.
  2. Replace the fuse as necessary.

Did you complete the repair?

--

Go to Step 21

--

14

Test for an intermittent and for a poor connection at the EVAP canister purge solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 18

15

Test for an intermittent and for a poor connection at the FTP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 19

16

Test for an intermittent and for a poor connection at the control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs and in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 20

17

Inspect the EVAP purge solenoid vacuum supply for a blockage or restriction.

Did you find and correct the problem?

--

Go to Step 21

Go to Step 18

18

Replace the EVAP purge solenoid. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .

Did you complete the replacement?

--

Go to Step 21

--

19

Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement .

Is the action complete?

--

Go to Step 21

--

20

Replace the PCM. Refer to Powertrain Control Module Replacement .

Is the action complete?

--

Go to Step 21

--

21

  1. Start the engine.
  2. Select the EVAP Purge/Seal function on the scan tool. Refer to Service Bay Test .
  3. Command the EVAP Purge/Seal function ON.

Does the FTP sensor indicate a reading of at least the first specified value for as long as the second specified value?

-28.20 mm Hg (-15.10 in H2O)

2 minutes

Go to Step 23

Go to Step 22

22

The EVAP System failed the EVAP Purge/Seal test.

Is there an EVAP system DTC that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 4

23

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