P0449

DTC P0449

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 P0449
- Evaporative Emission (EVAP) Vent Solenoid Control Circuit

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. 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

* DTC P0606 is not set.
* The ignition is ON or the engine is operating.
* The ignition 1 voltage is greater than 11 volts.
* The DTC runs continuously once the above conditions are met.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

DTC P0449 is a Type A DTC.

Conditions for Clearing the DTC

DTC P0449 is a Type A DTC.

Circuit/System Verification

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.

Circuit/System Testing

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.

Component Testing

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.

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