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Ask 17 years GM tech Your Own Question
17 years GM tech
17 years GM tech, GM master tech
Category: Pontiac
Satisfied Customers: 1918
Experience:  25 years automotive experience, 15 years with Saturn
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Code po449 came up on my car what do i need to check

Resolved Question:

code po449 came up on my car what do i need to check
Submitted: 6 years ago.
Category: Pontiac
Expert:  17 years GM tech replied 6 years ago.

ok p0449 is the evaporative emissions vent solenoid circuit, either open ckt or shorted

here is the info on how to diagnose it.

Without a scantool, you would just be guessing but if you want to do that I would replace the valve and see if the issue persists. If it does, then you need a scan tool to diagnose it....hope this helps. Please click accept

thank you

DTC P0449
Battery voltage is supplied to the 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

P0449

  1. With the ignition ON and the engine OFF, command the EVAP vent solenoid ON and OFF with a scan tool.
  2. Listen for a click when the valve operates. Verify that both the ON, and the OFF states are commanded.
  1. Turn OFF the ignition.
  2. Disconnect the EVAP canister vent solenoid valve.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive voltage circuit of the EVAP canister vent solenoid valve with a test lamp that is connected to a good ground.
    • If the test lamp does not illuminate, test the circuit for an open or for a short to ground.
  1. Connect a test lamp between the control circuit of the EVAP vent solenoid valve and the battery positive voltage circuit of the EVAP canister vent solenoid valve at the EVAP vent valve harness connector.
    • If the test lamp illuminates, test the control circuit of the EVAP canister vent solenoid valve for a short to ground.
  1. Command the EVAP canister vent solenoid ON and OFF.
    • If the test lamp does not illuminate with the commanded state of the valve, test the control circuit of the EVAP canister vent solenoid valve for a short to voltage or an open.
    • If the circuits and the control module test normal, replace the EVAP canister vent solenoid valve.

to replace the valve...graphic

  1. Lower the fuel tank enough on the right side in order to access the evaporative emission (EVAP) canister vent solenoid valve. Refer to Fuel Tank Replacement. It is not necessary to completely remove the fuel tank from the vehicle.
  2. Disconnect the EVAP canister vent solenoid valve tube quick connect fitting (2).
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