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

Connector End View Reference

Description and Operation

Evaporative Emission Control System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

1. With a scan tool, command the EVAP Vent Solenoid ON and OFF. The EVAP Vent Solenoid should respond to the scan tool commanded state.
2. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

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 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 and the ignition 1 voltage.
4. Ignition ON, with a scan tool, command the EVAP vent solenoid ON and OFF. The test lamp should respond to the commanded state.

⇒	If the test lamp remains ON all the time, test for a short to ground on the control circuit. If circuit/connections test normal, replace the ECM.

⇒	If the test lamp remains OFF all the time, test for a short to voltage or an open/high resistance on the control circuit. If circuit/connections test normal, replace the ECM.

5. If all circuits/connections test normal, test or replace the EVAP vent solenoid.

1. Measure for 18-28 ohms of resistance between the terminals of the EVAP vent solenoid.

⇒	If the resistance is not within the specified range, replace the EVAP vent solenoid.

2. Test for infinite resistance between each terminal of the EVAP vent solenoid and the EVAP vent solenoid housing.

⇒	If less than infinite resistance, replace the EVAP vent solenoid.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.