P0498

DTC P0498 or P0499

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provide an overview of each diagnostic category.

DTC Descriptors

DTC P0498
- Evaporative Emission (EVAP) Vent Solenoid Valve Control Circuit Open

DTC P0499
- Evaporative Emission (EVAP) Vent Solenoid Valve Control Circuit Shorted

Diagnostic Fault Information






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.

Conditions for Running the DTC

* The ignition is ON or the engine is operating.
* The DTCs runs continuously once the above conditions are met.

Conditions for Setting the DTC

DTC P0498

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

DTC P0499

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

Action Taken When the DTC Sets

* DTC P0498 and P0499 are Type A DTCs.
* The EVAP system will only purge during open loop.

Conditions for Clearing the DTC

DTC P0498 and P0499 are Type A DTCs.

Circuit/System Verification

1. With a scan tool, command the EVAP Vent Solenoid ON and OFF. You should feel or hear an audible click as the solenoid is commanded ON and OFF.
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 List.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector of the EVAP vent solenoid valve.
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 circuit.
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 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 valve.

Component Testing

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

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

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

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Evaporative Emission Canister Vent Solenoid Valve Replacement
* Programming and Relearning for ECM setup, and programming Programming and Relearning