DTC P0443 or P0449 (LF1, LFW)
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DTC P0443 or P0449 (LF1, LFW)
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DTC P0443
Evaporative Emission (EVAP) Purge Solenoid Valve Control Circuit
DTC P0449
Evaporative Emission (EVAP) Vent Solenoid Valve Control Circuit
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Diagnostic Fault Information
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Circuit
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Short to Ground
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High Resistance
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Open
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Short to Voltage
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Signal Performance
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Ignition 1 Voltage - Purge Supply
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P0443
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P0443
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P0443
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-
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-
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Battery Positive - Vent Supply
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P0449
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P0449
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P0449
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-
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-
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Evaporative Emission Purge Solenoid Control
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P0443
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P0443
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P0443
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P0443
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-
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Evaporative Emission Vent Solenoid Control
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P0449
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P0449
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P0449
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P0449
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-
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Circuit/System Description
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An ignition voltage is supplied directly to the evaporative emission (EVAP) canister purge solenoid valve. The engine control module (ECM) grounds the evaporative emission canister purge solenoid valve control circuit through an internal switch called a driver. The ECM monitors the status of the driver. The evaporative emission canister's solenoid valve is pulse width modulated (PWM). A scan tool shows the amount of ON time as a percentage.
Battery voltage is supplied to the EVAP canister vent solenoid valve. The ECM grounds the EVAP canister vent solenoid valve control circuit through an internal switch called a driver. The ECM monitors the status of the driver. A scan tool will display the commanded state of the evaporative emission canister vent solenoid valve as ON or OFF.
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Conditions for Running the DTC
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The system voltage is between 9-18 V.
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DTCs P0443 and P0449 run continuously when the above conditions are met.
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Conditions for Setting the DTC
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The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for a minimum of 5 seconds.
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Action Taken When the DTC Sets
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DTCs P0443 and P0449 are Type B DTCs.
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Conditions for Clearing the MIL/DTC
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DTCs P0443 and P0449 are Type B DTCs.
Schematic Reference
Engine Controls Schematics (3.0L (LF1))
Engine Controls Schematics (2.8L (LAU))
Description and Operation
Evaporative Emission Control System Description
Connector End View Reference
Component Connector End Views
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References
for scan tool information
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Circuit/System Verification
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P0443
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1.
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Ignition ON, engine OFF, you should hear a clicking sound when the EVAP canister purge solenoid valve is commanded to 50 percent with a scan tool. The clicking sound should stop when the EVAP canister purge solenoid valve is commanded to 0 percent. The rate at which the valve cycles should increase when the commanded state is increased, and decrease when the commanded state is decreased.
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2.
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Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
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P0449
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1.
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Ignition ON, engine OFF, command the EVAP vent solenoid ON and OFF with a scan tool.
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2.
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Listen for a click when the valve operates. Verify that both the ON, and the OFF states are commanded.
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3.
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Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
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1.
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Ignition OFF, disconnect the harness connector at the Q 12 EVAP canister purge or the Q 13 EVAP vent solenoid valve.
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2.
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Ignition ON, verify that a test lamp illuminates between the voltage supply circuit terminal B for vent or 1 for purge valve and ground.
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3.
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If the test lamp does not illuminate, test the voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and the voltage supply circuit fuse is open, test or replace the evaporative emission canister purge or vent solenoid valve.
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4.
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Connect a test lamp between the voltage supply circuit terminal B for vent or 1 for purge valve and the control circuit terminal A for vent or 2 for purge valve.
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5.
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Command the evaporative emission canister purge solenoid valve to 50 percent with a scan tool, or the evaporative emission canister vent solenoid valve ON and OFF. The test lamp should respond to the command.
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6.
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If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
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7.
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If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
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8.
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If all circuits test normal, replace the appropriate solenoid valve.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
