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.

The ECM detects the EVAP vent solenoid control circuit is open, shorted to ground, or shorted to voltage.

DTC P0449 is a Type A DTC.

DTC P0449 is a Type A DTC.

Schematic Reference

Engine Controls Schematics

Description and Operation

Evaporative Emission Control System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

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.

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.

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.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.