[A8] 99 a8 emissions problem

[Jason Wilkerson]

Guys,
 
I have an issue with my 1999 A8. The CEL came on the other day. Two codes - 
 
    16839/P0455 - Evap system, large leak
    16825/P0441 - Evap system, incorrect flow, intermittant.
 
I have checked the following:
 
    Purge valve, pulled vac on the engine side, no leaks. Tested electrical operation, works fine. Tested on car and it modulates     like it should - OK
 
    Fuel expansion tank for leaks, visually and with pressure - OK
    
    Fuel cap and neck - OK.
 
    Fuel tank lid with seals for sender and fuel pump - OK.
    
    Carbon canister under spare tire - OK.
 
    Evap test pump - Not sure?
 
Here is the run down:
 
    Before the CEL illuminated, I was hearing a 'whining' sound coming from the pass rear wheel. Turns out it is some sort of check valve in the expansion tank above that wheel. I don't think this is the problem, but just a symptom.
 
    Not sure if it is relevant, but before I started to hear the 'whining' and before the CEL, I backed into a building. It was not hard and really didn't even put a mark on the car, but - it would seem that it was about the same time that this happened and the same time that it currently takes to reset the CEL.
 
    I pressure checked the whole fuel system last night and found nothing leaking.
 
    I'm leaning toward the evap test pump - I may have to buy one anyway because I broke one of the fittings off trying to remove it to look for anything obvious.
 
SO - any suggestions? I am at a loss. Thanks in advance.