P0449
DTC P0443 or P0449
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0443
- Evaporative Emission Purge Solenoid Valve Control Circuit
DTC P0449
- Evaporative Emission Vent Solenoid Valve Control Circuit
Diagnostic Fault Information
Circuit/System Description
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 purge solenoid valve is pulse width modulated (PWM). A scan tool will display the amount of ON time as a percentage.
Battery voltage is supplied to the evaporative emission canister solenoid valve. The ECM grounds the evaporative emission 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.
Conditions for Running the DTC
* The ignition is ON.
* The system voltage is between 9-18 V.
* DTCs P0443 and P0449 run continuously when the above conditions are met.
Conditions for Setting the DTC
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 s.
Action Taken When the DTC Sets
DTCs P0443 and P0449 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0443 and P0449 are Type B DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics ([1][2]Electrical Diagrams)
Description and Operation
Evaporative Emission Control System Description (Evaporative Emission Control System Description)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Troubleshooting with a Test Lamp (Troubleshooting With a Test Lamp)
* Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
P0443
1. Ignition ON, engine OFF, you should hear a clicking sound when the evaporative emission canister purge solenoid valve is commanded to 50 % with a scan tool. The clicking sound should stop when the evaporative emission canister purge solenoid valve is commanded to 0 %. The rate at which the valve cycles should increase when the commanded state is increased, and decrease when the commanded state is decreased.
2. 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.
P0449
1. Ignition ON, engine OFF, command the evaporative emission vent solenoid valve to Not Venting and Venting with a scan tool.
2. Listen for a click when the valve operates. Verify that both the Venting and the Not Venting states are commanded.
3. 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.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the Q12 evaporative emission canister purge or the Q13 vent solenoid valve.
2. Ignition ON, verify that a test lamp illuminates between the voltage supply circuit terminal and ground.
• 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 solenoid valve.
3. Connect a test lamp between the voltage supply circuit terminal and the control circuit terminal.
4. Command the EVAP canister purge solenoid valve to 50 % with a scan tool, or the EVAP canister vent solenoid valve Venting and Not Venting. The test lamp should respond to the command.
• 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.
• 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.
5. If all circuits test normal, replace the appropriate solenoid valve.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Evaporative Emission Canister Purge Solenoid Valve Replacement (Service and Repair)
* Evaporative Emission Canister Vent Solenoid Valve Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming