what is a code p0449
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2007 Hummer H2 Question: check engine light
Answer #1mastertech6371 January 18, 2011, 12:38Master
this is a chart for you.
A battery positive is supplied to the evaporative emission (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. If the control module detects an incorrect voltage for the commanded state of the driver, this DTC sets.
The table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister vent solenoid valve.
This diagnostic procedure supports the following DTC:
DTC P0449 Evaporative Emission (EVAP) vent Solenoid Control Circuit
Conditions for Running the DTC
The engine speed is more than 400 RPM .
The system voltage is between 10-18 volts .
DTC P0449 runs continuously once the above conditions are met.
Conditions for Setting the DTC
The control module detects that the commanded state of the driver and the actual state of the control circuit do not match.
The above conditions are present for a minimum of 5 seconds .
Action Taken When the DTC Sets
The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.
Step 1 - Step 10
Step 11 - Step 15
The numbers below refer to the step numbers on the diagnostic table.
Listen for a click when the valve operates. Verify that both the ON and the OFF states are commanded.
This step verifies that the control module is providing ground to the EVAP canister vent solenoid valve.
This step tests if the EVAP canister vent solenoid valve control circuit is grounded.