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Q: Engine Light P0449 on 2005 Chevrolet Tahoe

Engine Light on constantly. Codes Read at Auto Zone: P0449 EVAP purge/vent solenoid circuit condition. Is this a dealer only part?
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Vehicle Application: 2005 Chevrolet Silverado 1500 5.3L, FLEX, Vin Z, Eng Cfg V8

Customer Concern: Power train Control Module (PCM) code P0449 setting.
Tests/Procedures: 1. Command the evaporative vent solenoid on/off, listen for click at the vent solenoid.

2. Check for 13-14 volts to the evaporative vent solenoid on the Pink wire with the engine running.

3. Test the evaporative solenoid resistance, solenoid disconnected. Should have 20-30 ohms.

4. If no click from the evaporative vent solenoid when commanded on with a scan tool, but the solenoid checks OK and the power feed is OK, then test the evaporative vent solenoid control wire, White.

5. Check the White wire from the PCM, pin 45, green connector, to C152, 12 pin connector, pin F, under the Under hood Bussed Electrical Center (UBEC).
Potential Causes: Connector
Evaporative Vent Solenoid
Vent Solenoid Wiring

Tech Tips: The evaporative vent solenoid is back by the fuel tank. Wire rubbed through on the frame. Repairing the wire solved the problem.
Diagnostic Codes: P0449
Vehicle Application: 2007 Chevrolet Tahoe LS 5.3L, FLEX, Vin 0, Eng Des LMG

Customer Concern: DTC P0449.
Tests/Procedures: 1. Check the TCCM-battery fuse 14 in the under hood fuse block.

2. Check for Battery Voltage (B+) at the vent solenoid pin B Red/White wire.

3. Check the White wire at the vent solenoid for a ground with the vent solenoid commanded off.

4. If the White wire has a ground with the vent solenoid commanded off, unplug the C1 connector at the Engine Control Module (ECM). If the ground is gone replace the ECM, if there is still a ground on the White wire with the ECM unplugged, check for a short to ground between the vent solenoid and the ECM.
Potential Causes: Grounded Circuit — Short to ground.
Electronic Control Module (ECM)
Vent Control Solenoid

Tech Tips: P0449 Battery voltage is supplied to the Evaporative Emission Control System (EVAP) canister vent solenoid valve. The control module grounds the EVAP canister vent solenoid valve control circuit to close the valve by means of an internal switch called a driver. The scan tool displays the commanded state of the EVAP canister vent solenoid valve as ON or OFF. The control module monitors the status of the driver.
Diagnostic Codes: P0449
This may not mean that you need to change that solenoid. There may be something else going on in the evaporative system. I recommend getting a technician to diagnose rather before swapping out parts. Check the RepairPal Check Engine Light article for more info on what may be going wrong:
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