Major evap leak?
 

I bought my 01 A6 2.7T from auction as a flood car due to the infamous plugged drain in the firewall. The only damage found was that water had gotten into the tcm I changed the tcm and found no other issues. Also since the car was at 88k I went ahead and did the timing belt kit and cam tensioner and valve cover seals.

I drove the car for two days and all was well on the third day I had a cel light come on I forgot to write down the code number but it said it was a (major evap leak major leak in the evaporator system) When I did the initial work and checked codes this code was not showing then there were several intermittent codes for random misfires and of course the codes for the tcm faults. I did install new plugs and havent had any codes come back. I did find a receipt from an inde repair shop in the car showing new brakes had been installed just a couple days before the flooding problem and they noted on the reciept that the cel light was on but no additional info was provided.

Anyone have any ideas about where the leak could be? could I have left something off when I put the car back together? Could it be a bad fuel cap?

Any ideas on where to start would be greatly appreciated.

Start with getting VagCOM and clearing the codes- then see what comes back
Of course the gas cap could cause a leak but you won't know until you clean up the debris from earlier problems.

Try tightening your gas cap. The Audi is sensitive to this.

Bob

evap purge valve is usually the cause, if the cap is tight.

you can test this using a vacuum pump / gauge.

I have cleared all the old codes and the major evap leak is the only new code that pops up.

I have tried the gas cap even switching it with the one from my daughters car (sometimes its nice that we drive the same cars lol)

Is the purge valve the one that is located on the right side of the silver air tube on top of the engine near the back?

I am in the process of changing the timing belt on my daughters car and should finish tonight then I can get mine back in to dig back into this issue of course these Audis always seem to have issues at the same time lol.