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.
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This step verifies the electrical operation of the EVAP canister purge solenoid.
-
This step tests the function of the EVAP canister purge solenoid.
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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.
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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.
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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 | |
2 | Install a scan tool and check for DTCs. Is a DTC P0450. P0451, P0452, or P0453 present? | -- | Go to Step 3 | |
3 |
Is DTC P0441 captured in the Freeze Frame/Failure records? | -- | Go to Step 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 | |
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 |
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 |
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 | |
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 (-10.00 in H2O) | Go to Diagnostic Aids | Go to DTC P0446 | |
10 |
Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 13 |
11 |
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 |
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 | -- |
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 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? | -- | System OK | |
