I recently got a 449 code and it is the EVAP solenoid. Replaced it and the gas cap but am still getting the same code in spite of clearing the code with my code reader. Anyone have any suggestions? 2007 2500 4.8 engine.

 

Check the vacuum lines, those to/from the solenoid.

 

to clarity...you replaced which solenoid? the evap has a purge and vent solenoid .the code is for an electrical fault with the vent solenoid circuit.
the pcm reads the state of the vent solenoid as either closed (low voltage) or open (high voltage). the fault sets when the state doesn't match what is commanded.
to test this as per the service manual you need a bi-directional scan tool that can command the vent open and closed. without a scan tool you should start by checking the power and grd wiring to the solenoid.

check the power side
-key on engine off...with a test light clipped to a good grd…remove the vent solenoid connector and probe the power wire red/white...the test light should illuminate. if not, check the vent solenoid fuse #34 10amp. if the fuse is good...the wiring is open.

check the grd wire.
-disconnect the battery negative cable. remove the pcm c2 connector and ohm check the wires from the vent solenoid white wire to the pcm pin 45. if the wire is open...repair or replace the wire. if the wire is good...you may need a pcm...have a shop perform further diagnosis.

 

I neglected to mention this. I can clear the code, light goes off, and can drive the vehicle any distance with no visible check engine light. But if I turn the engine off then restart, the light comes back on. Where is the vent solenoid located. I replaced the complete unit thats located on the drivers side just in front of the tank. Pictured is the old one and a new one. That particular new one did not fit so I returned it and the parts guy kept searching till He found the correct one.

 

it requires two consecutive trips/drive cycles with the fault active for the code to set and illuminate the mil. the first trip and test failure a pending code is set but mil is not illuminated...2nd failure mil is turned on.

 

Just spent the last hour poking and prodding and have narrowed it down to no power to unit. I removed the unit from vehicle and applied power to solenoid and it is functioning. I cannot find a relevant fuse in either fuse box. If there is one under what name would it be listed?

 

done...read post 3lol

 

There was a break in the power wire that powers the solenoid. It was about a foot back from the plug in on the solenoid.

About the post 3. I inquired in layman's terms and You responded in technical terms.