2002 Mazda MPV engine Light on and off again

2002 Mazda MPV Engine Light comes on. At first I thought we left the gas cap off or did not tighten it down. I waited all week to see if the light would go out but no luck. I filled the tank up with gas and the light went out right away on start up. We drove the car for several days and the light went back on. I then filled the tank again and the light went right out on start up. I thought it might be a bad gas cap so I replaced it. Again we drove the car for several more days and the light went on. Filled up again and lights out. We did notice that the light stayed off longer when the weather is colder. The light usually goes out with in the first 1/4 tank depending on how cold the days are.

The mechanic that is working on it now says the code is P0443. He checked everything mechanical finding nothing. Now he is claiming it is an electrical problem and needs more time $$$ to find it. I am hoping not to spend allot of money in diagnosing this problem. Any one else dealing with this or have any ideas?

Here is what the code means:


Read the list of possible causes. The fix could be as simple as replacing a faulty purge valve.