Well Yesterday I had two new tires put on my car. After i picked it up from the place my gas light went on...so i stopped at the nearest sunoco and filled up.
I drove about 3 miles and shut the car off. 6 hours later i started the car up to go home. About a mile later i thew a CEL. I ran back to the shop scanned it with the snap-on scanner and got code 17883: Evap System Malfunction: No Signal. I figured i might have forgot to tigten my gas cap, so i went back.. Tightened it 3 clicks, cleared the code and went home. After i started the car again and drove a block or two i threw the same code again.
Now from what i have found from searching normally the code is something a little different and it would say Small Leak, or Large Leak. However, i have neither of those. I have NO SIGNAL, which isnt that common from what i gather.
So after much reading and all, i thought maybe it was the N80 valve. The n80 valve stays closed when the ignition is off holding all the vapors and pressure toward the rear of the car. When you start the car the Valve opens releasing the vapor/vacuum into the whole system.
So i figured the n80 could be the culpurit because if the valve is getting stuck closed and not releasing the pressure when i start the car...Then the Evap Pump would not recieve any signal, hence the NO SIGNAL code.
Today i troubleshooted the n80 valve and i think its fine. I ran a test through the snap-on scanner which opens and closes the valve constantly for 30 seconds. If i applied vacuum on the valve with a mityvac, everytime the valve would click i'd lose a little vacuum. Not to mention if you put your hand on it you can feel the selenoid clikcing inside. So i figured the valve is operating correctly, or opening and closing atleast. Could it still have a possible malfunction when the audi evap system calls upon it? Sure, but i think its pretty unlikely.
So the next culpurit which i didnt get to yet is the Evap pump in the driver side wheel well. Im going to pull my tire off today or tomrorow to a get look in there at the electrical connectors and the pump. Im guessing if the part of the pump failed that detects the Vacuum, that could be causing it also. So i may try replacing the pump on monday.
Im just making this post to see if anyone else has had this same exact code...and what they did to correct it. Also to see if anyone has any other thoughts on how to correct the problem.
Any help is greatly appreciated.
Thanks in advance
John

 

John,
were you able to find the problem? I just got the same code on my 2000 S4.

 

There might be a small leak in the line some where.

You can also unplug the N80, clear the code, and see if pops right back on, or give you another code.
While the valve may be functional it still might be on it's way out & giving a much lower resistance, and that's setting off the code.

Did you pressure test of the lines off the N80?