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.

P0498

The ECM detects the EVAP vent solenoid valve control circuit is open.

P0499

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

DTC P0498 and P0499 are Type A DTCs.

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 Wwith a scan tool. You should feel or hear an audible click as the solenoid is commanded ON and OFF.
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 at the EVAP vent solenoid valve.
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 valve ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	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 valve.

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 valve.

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

⇒	If not the specified value, replace the EVAP vent solenoid valve.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.