P0449
DTC P0449
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0449
- Evaporative Emission (EVAP) Vent Solenoid Control Circuit
Circuit/System Description
The evaporative emission (EVAP) vent solenoid valve is used for EVAP system diagnostics. The EVAP vent solenoid valve is a normally open valve. Ignition voltage is supplied directly to the EVAP vent solenoid valve. The engine control module (ECM) controls the solenoid by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.
Conditions for Running the DTC
* DTC P0606 is not set.
* The ignition is ON or the engine is operating.
* The ignition 1 voltage is greater than 11 volts.
* The DTC runs continuously once the above conditions are met.
Conditions for Setting the DTC
The ECM detects the EVAP vent solenoid control circuit is open, shorted to ground, or shorted to voltage.
Action Taken When the DTC Sets
DTC P0449 is a Type A DTC.
Conditions for Clearing the DTC
DTC P0449 is a Type A DTC.
Reference Information
Schematic Reference
Engine Controls Schematics (MR140 w/o Throttle Actuator Control) (Electrical Diagrams)Engine Controls Schematics (MT34 w/Throttle Actuator Control) (Electrical Diagrams)Engine Controls Schematics (Hatchback) (Electrical Diagrams)
Description and Operation
Evaporative Emission Control System Description (Evaporative Emission Control System Description)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Command the EVAP Vent Solenoid ON and OFF with a scan tool. The EVAP Vent Solenoid should respond to the scan tool commanded state.
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.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector of the EVAP vent solenoid.
2. Ignition ON, verify a test lamp illuminates between the ignition 1 voltage circuit terminal 2 and ground.
• If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.
3. Ignition OFF, connect a test lamp between the control circuit terminal 1 and the ignition 1 voltage circuit terminal 2.
4. Ignition ON, command the EVAP vent solenoid ON and OFF with a scan tool. The test lamp should respond to the commanded state.
• If the test lamp is always ON, test for a short to ground on the control circuit. If the circuit tests normal, replace the ECM.
• If the test lamp is always OFF, test for a short to voltage or an open/high resistance on the control circuit. If the circuit tests normal, replace the ECM.
5. If all circuits test normal, test or replace the EVAP vent solenoid.
Component Testing
1. Ignition OFF, disconnect the harness connector of the EVAP vent solenoid.
2. Test for 18-28 ohms of resistance between the control terminal 1 and the ignition 1 voltage terminal 2.
• If not within the specified range, replace the EVAP vent solenoid.
3. Test for infinite resistance between each terminal and the EVAP vent solenoid housing.
• If not the specified value, replace the EVAP vent solenoid.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Evaporative Emission Canister Vent Solenoid Valve Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for engine control module replacement, setup, and programming