DTC P0449, P0498, or P0499. Chevrolet Equinox 2008

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2008 🢒 Equinox 🢒 Power and Signal Distribution 🢒 Wiring Systems and Power Management 🢒 DTC P0449, P0498, or P0499

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC P0449: Evaporative Emission (EVAP) Vent Solenoid Valve Control Circuit

DTC P0498: Evaporative Emission (EVAP) Vent Solenoid Valve Control Circuit Low Voltage

DTC P0499: Evaporative Emission (EVAP) Vent Solenoid Valve Control Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ignition Voltage	P0498	P0449	--	--
EVAP Canister Vent Solenoid Valve Control Circuit	P0498	P0449	P0499	--

Circuit/System Description

The evaporative emission (EVAP) canister vent valve is used for EVAP system diagnostics. The EVAP canister vent valve is a normally open valve. Battery positive voltage is supplied directly to the EVAP canister vent 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

•	The engine speed is greater than 80 RPM.

•	The ignition voltage is between 10-18 volts.

•	The ECM has commanded the EVAP canister vent valve ON and OFF at least once during the ignition cycle.

•	The DTCs run continuously when the above conditions are met.

Conditions for Setting the DTC

DTC P0449

The ECM detects the voltage on the EVAP canister vent valve control circuit is between 2.6-4.6 volts when the driver is commanded OFF. The condition exists for 4 seconds, or a cumulative of 30 seconds.

DTC P0498

The ECM detects the voltage on the EVAP canister vent valve control circuit is less than 2.6 volts when the driver is commanded OFF. The condition exists for 4 seconds, or a cumulative of 30 seconds.

DTC P0499

The ECM detects the voltage on the EVAP canister vent valve control circuit is greater than 4.6 volts when the driver is commanded ON. The condition exists for 4 seconds, or a cumulative of 30 seconds.

Action Taken When the DTC Sets

•	DTCs P0449, P0498 and P0499 are Type B DTCs.

•	The EVAP system will only purge during Open Loop.

Conditions for Clearing the DTC

DTCs P0449, P0498 and P0499 are Type B DTCs.

Reference Information

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Command the EVAP vent solenoid valve ON and OFF with the scan tool. An audible click should be heard when changing between the commanded states.
Start the engine, observe the scan tool EVAP Vent Solenoid Valve Circuit Test Status parameters. The circuit test status parameters should display OK or Not Run.
Start the engine, observe the DTC information with a scan tool. DTCs P0449, P0498, or P0499 should not set.
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

Ignition OFF, disconnect the harness connector at the EVAP vent solenoid valve.

Note: The ignition circuit supplies voltage to other components. Make sure you test all circuits for a short to ground, or test all components for being shorted that share the ignition circuit.

Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal A and ground.

⇒	If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition voltage circuit fuse is open, test all components connected to the ignition voltage circuit and replace as necessary.

Ignition OFF, connect a test lamp between the control circuit terminal B and the ignition voltage circuit terminal A.

Note: The control circuit for the EVAP vent solenoid valve is pulled-up to voltage within the ECM, 2.6-4.6 volts on the control circuit is normal.

Ignition ON, use a scan tool to command the EVAP vent solenoid valve ON and OFF. The test lamp should turn ON and OFF.

⇒	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.

Test for 2.6-4.6 V between the control circuit terminal B and ground.

⇒	If not within the specified range, replace the ECM.

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

Component Testing

Measure for 20-24 Ω between the terminals of the EVAP vent solenoid valve.

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

Measure the resistance between each terminal of the EVAP vent solenoid valve and the EVAP vent solenoid valve housing. The DMM should display O.L.

⇒	If less than the specified value, replace the EVAP vent solenoid valve.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Evaporative Emission Canister Vent Solenoid Valve Replacement

•	Control Module References for ECM replacement, setup, and programming