docmusolf

2 Faults Found:
16705 - Engine Speed Sensor (G28): Implausible Signal
P0321 - 35-10 - - - Intermittent
16839 - EVAP System: Large Leak Detected
P0455 - 35-00 - -

skiracer

If the gas cap is tight, you may have a problem with the fuel level sender seal in the trunk. Does your trunk smell like gas? As always, clear the codes and watch to see if they return.

docmusolf

What classifies as the EVAP system? No smell of gas.

Cjshutts

They can be hard to find. In terms of likelihood:
1. Gas cap
2. Fuel sending unit cover on audipages
3. Purge regulator valve (under the hood passenger side in the front about the size of a spool of thread). This sometimes fails to close during the leak test. They are $76 on line. You can test this before replacing.
4. Zillions of vacuum lines, well documented in Bentley

I would start with a new gas cap from NAPA for $4.50.

I have an intermittant gross leak which occurrs only between 3/4 and 1/2 tank. Very hard to find.. I am going to pressurize the system in a couple of weeks.

my97A8

I reset the 16705 Engine Speed Sensor (G28): Implausible Signal a number of time. About three weeks ago my can would simply shut off then turn back on at any speed. I got no reading. It got worse to the point that I got stuck - after a small amount of time it would start. I then got a signal that the Engine Speed Sensor: No Signal. I went to replace the sensor but I got three different units. As it turned out for me the hardness' were not the same and Audi does not make this any longer but does have an interface to connect the two together. Interesting enough is that this sensor is located closely between the tranny and exhaust pipe. I opened the sensor wire up and found the small wires with in to be deteriorating. My problem of shutting down is now solved.

docmusolf

do you have pics of this procedure