So the code today was p3081 which is saying that the engine temp is too low.

They also noticed that the coolant fan is continuously running but they think that the coolant sensor they replaced on Monday that controls this might be faulty.

They are going to replace the sensor and reset the CEL and see what happens from there.... any advice?

 

The codes you are supplying are the generic OBD2 codes.
The lack of VAG codes makes me suspect the shop is not equipped to handle VAG's.

Coolant temperature Sensor (on top back some passenger side cross coolant pipe)
Radiator thermo switch - bottom passengers side of the radiator.

Cooling fan - your referencing the radiator fan ? (on the radiator, engine side)

(look for my thread "Radiator fan redundancy" - you might find it helpful)

 

Where is the Oil Temp sending unit located on 2001 Audi Allroad? I have warning indicator - chimes early in engine running, and the oil temperature guage will drop from reading to '0' and stay there. Coolant temp is fine and oil LEVEL is fine - just seems to be oil temperature unit fault. I have purchased the unit, it's on it's way. Thanks for help.

 

I think it is also called oil LEVEL sensor, it serves TWO DUTIES, teperature and level...

The sensor is on the bottom of the oil pan. If you're laying under the car, it sits into a recess in the bottom of the pan. It's the only thing there besides the nice, shiny aluminum. Bolts and a gasket that holds it in place. Take the bolts off and with a little wiggling it'll come out. New gasket, new sensor, make sure you clean the seating surface of the gasket well or else you'll be chasing leaks forever. I have no idea what the torque specs on the bolts are; just be careful, as the pan is aluminum.

Drain your oil first. If not, it's going to drain all over you when you pull the sensor out!

 

If its like my 12v ,the only thing that can make the electric fan run is the fan thermo switch. I can't believe a mechanic would be that ignorant, but it needs replaced regardless.

If a new cool temp sensor isn't fixing the problem, then its either the gauge, faulty wiring, or the engine is actually having coolant temp regulation issues.