Vag'd it. P0118: Engine Coolant Temp.Circ High Input. Time to replace coolant temp sensor?

 

Probably, but what are your actual temps from the HVAC readout?

 

they seemed like normal temps, i cant remember the exact temp when i checked it this morning

 

Hey how do you get the HVAC Readouts?

 

Go to Youtube and search "Audi TT 49c" and you will see how to read coolant temp on the HVAC display.

 

I picked up a 2001 in January. I drove it from UT to CA and the temp remained low on the gauge the entire drive. I knew I was going to have to address it. I replaced the temperature sensor, the thermostat and the thermostat housing pipe connected to the thermostat all at once. It was my first time doing it. The coolant made a mess, as I expected, but it addressed my problem. I had read the thermostat can often get stuck open or closed. In my case it was likely stuck open. I followed a couple tips I had found online to replace the plastic thermostat housing with a metal one. It also correctly suggested I be sure to get a spare dipstick, as that assembly can easily break while you’re working in that area of the motor. One video I watched suggested I needed to remove several other parts to get to the bolts at the base of the pipe leading to the thermostat. With the right tools I didn’t have to remove but a few items. By right tools, a ratchet with a 2-way pivoting head as well as a ratchet extension allowed me to get to the bolts on either side of the thermostat housing without issue. Thermostat and sensor both work great now. As far as the coolant, I had a catch bin, but it wasn’t big enough. Fortunately I had a tarp down to catch everything so it didn’t flow on the floor.

For my 2001, I found these to be the parts I needed:
Coolant Temperature Sensor - 059919501AKT2 VW/Audi - https://www.ecstuning.com/b-genuine-...059919501akt2/Thermostat Replacement with Thermostat Housing - https://www.ecstuning.com/b-assemble...660ecs01-01kt/
Dipstick funnel (commonly breaks when you replace the thermostat): https://www.ecstuning.com/b-assemble.../06a115611q-1/

With all that said, if you’re running hot, which is the opposite of my issue, you may have a different problem where your radiator isn’t cooling the engine effectively.