Ok.. so thought I would throw this out there.. I have a 99-996 that was running fine.. maybe a little warm on excessively warm days.. but all within the normal temp range. One day I came out and found the car was dripping a little coolant under the driver side exhaust. Took the car in and after far too long to diagnose.. despite me telling the mechanic I thought it was the expansion tank.. the tank was swapped out. I get the car back and now the temp gauge light it flashing it’s red light slowly and the car is not heating up correctly. I drove it about 40 miles this morning and the temp was sitting at no more than 110 on the gauge.. it was ice cold for most of the drive and I sat in a small amount of traffic and it rose slightly and then started coming back down again when I started moving. It was not overly cold out.. 55- 60 degrees Fahrenheit outside temp. Coolant level is fine so I’ve read the light flashes slowly when it’s low.. but I’m lost on why now it’s not temping the right way. The mechanic said he checked all the sensors and it came with a new sensor I guess when he swapped out the tank.. wanted to dismantle the speedometer to get to the bottom of the flashing light and I said no. Just curious if anyone has seen or experienced anything like this? I appreciate your time!