What is the code now? On the left side of this post is a place to look things for some good information. Under encyclopedia you will find the 'exhaust & emission' labeled, and click on that for information about the EVAP system and the operation of the components. Just because it called for a vent valve, does not mean the vent valve is the problem, you have another problem that needs to be diagnosed. I f you will google p0449 Ford explorer, there is a listing for a RepairPal article on the complete understanding of this code and the proper way to consider the fault code. Good Luck.
You people only see what you want to see and hear what you want to hear. You have your answer right below here. I don't know why I even care, you won't even listen. You deserve to have your light on. Good luck.
Trying to look up the code in Mitchell P0449 for a 2003 Mountaineer shows it to not be plausible. Is there a typo? Other cars can set that particular code and it would be a vent solenoid "circuit" issue. Which would be correctly tested by checking for power to the solenoid, and then using a scan tool bi-directional controls to prove that the computer can turn the solenoid on. The second diagnostic event "na 01/01" has to be a scanner issue. You may want to try a different tool.
I was there before, and know the code does not exist for the Ford line. When I stated that, I was told to google it, and there is information on the Ford line, so that's why I asked them to find this information so they could get an idea that the vent solenoid is not necessarily the fix.