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.

Condition

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.

Cause

Dirt and dust intrusion into the EVAP canister vent hose assembly, resulting in restricted air flow, may cause this condition.

Correction

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.

1999-2003 Model Year (Use Service Kit P/N 19152345)

1. Raise the vehicle. Suitably support the vehicle.
2. Disconnect the EVAP canister vent valve electrical connector, if equipped.
3. Disengage the two vent valve pipe clips securing the pipe to the underbody. Remove the clips from the underbody and discard.
4. Disconnect the vent valve pipe at the EVAP canister.
5. Remove and retain the EVAP canister vent valve bracket mounting bolt.
6. Remove the complete EVAP canister vent valve assembly with bracket attached and discard.
   
   
   

   Important: The new canister vent valve will be installed in a new location, outside of the frame.

7. Position and secure the new valve assembly to the frame bracket on the outside of the frame using the existing hole and mounting bolt.

   Tighten
   Tighten the bracket mounting bolt to 12 N·m (106 lb in).

8. Connect the vent valve pipe to the EVAP canister.
9. Install the two vent valve pipe clips into the existing underbody holes.
10. Connect the EVAP canister vent valve electrical connector, if equipped.
11. Attach bulk 5/8" heater hose to the vent valve port and secure using a clamp. Run a length as needed along the frame rail routing to the area above the transmission.
12. Cut the hose to determined length and install the supplied filter box. Secure using a clamp.
    
    
    
13. Secure the filter box to the fuel lines above the transmission using a tie strap. The filter box opening should be pointing downward.
14. Tie strap the hose as needed along the frame rail in order to keep the hose away from pinch-points and heat sources.
15. Lower the vehicle.

2004-2007 Model Year (Use Service Kit P/N 19152349)

1. Raise the vehicle. Suitably support the vehicle.
2. Disconnect the EVAP canister vent valve electrical connector.
3. Disconnect the canister pipe from the vent valve.
4. Push in the retainer and remove the existing canister vent valve from the fuel tank clip or mounting bracket. Discard the old valve.
5. Cut back the existing canister pipe approximately 51 mm (2 in) to remove the quick connect end.

   Crew Cab Short Box Shown Below, Other Configurations Similar

   
   
   
   

   Extended Cab Short Box Shown Below, Other Configurations Similar

   
   
   
   
6. Install the new canister vent valve to the fuel tank clip or mounting bracket.
7. Cut bulk 5/8" heater hose to a length of approximately 76 mm (3 in). Install the hose between the vent valve and the canister pipe and secure using clamps.
8. Attach bulk 5/8" heater hose to the vent valve port and secure using a clamp. Run a length as needed along the frame rail routing to the area above the transmission.
9. Cut the hose to determined length and install the supplied filter box. Secure using a clamp.
   
   
   
10. Secure the filter box to the fuel lines above the transmission using a tie strap. The filter box opening should be pointing downward.
11. Connect the EVAP canister vent valve electrical connector.
12. Tie strap the hose as needed along the frame rail in order to keep the hose away from pinch-points and heat sources.
13. Lower the vehicle.