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There are no known issues or service bulletins with these codes. Click on the link below for more diagnostic info on the codes. The VSV's are easy to check. One is for evap purge and one is monitoring canister or tank pressure.
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You are probably looking at 1 to 2 hours of labor, times your local rates. Or you could just replace the valves one at a time and save the labor in diagnostics and take a chance. You would have to call the dealer for an exact price on the valves. If the gas cap was leaking it will set a P0440 with the other codes. Any time the P0440 is missing from the equation the problem is in one of the valve mentioned or the canister. 90% of the time it is one of the VSV's.
The OVR (On board Vapor Recovery) is not working check the air drain tube on the canister it is designed to take the vapors that come from the tank when filling and run them through the charcoal canister to clean them and the allow the pressure to escape to the atmosphere. If the air drain hose is plugged (usually by a spider nest or a wasp mud dobber) the tank will be difficult to fill. Click on the diagram below.