ok, the code P0449 indicates a problem with the vent sol. being either stuck on or off. this is usually caused by road dirt getting into the vent sol. due to it's mounting location obove the fuel tank. you have two options, one is just simply replace the vent sol. the other and the correct repair is to install a kit and a filter to the vent sol. do this wont happen again. i have included a service bulletin which shows how to do this. although the info states for a code PO446, it still applies.
Some customers whose vehicles are operated in dusty type environments, such as farming or mining off-road type applications, may comment about the illumination of the instrument panel SES light, with a DTC of P0446 (Restricted/Blocked EVAP Vent Path) being set.
Dirt and dust intrusion into the EVAP canister vent hose assembly, resulting in restricted air flow, may cause this condition.
After following the Service Information diagnostics for P0446 and determining that the EVAP canister vent valve is the cause of the SES light, replace the existing EVAP canister vent valve assembly with a new assembly. This new assembly is a sealed unit that is designed to be vented through a remote filter box. To ensure correct installation, follow the procedures below.
Important: The new canister vent valve will be installed in a new location, outside of the frame.
Tighten Tighten the bracket mounting bolt to 12 N·m (106 lb in).
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.