On my way up the driveway last night after a drive I managed to stall the car and upon restarting it I had a code pop up on my dash signaling a temp failure indicator along with my water temp gauge bottoming out and the little amber warning light next to it start blinking. I shut the car off and restarted it only to get the same set of warnings on the dash. This is the first time this has ever happened and when I posted it in a 996 facebook group and I was told that my coolant temp sensor could be out, but after searching a bit it seems that this could also be a low voltage/post stall issue and it could fix itself. Has anybody else had this issue?

 

My car has a similar but different issue. When driving when outside air temp is low this same warning condition occurs just as the temp gauge starts to move off full cold. After a few mimutes it clears itself. Replaced the temp sensor, cleaned all grounds, cleaned all connections relating to the sensor and resevour. Going on for over a year. Still occurs. Hope you find a cause.

 

Low on coolant? Going uphill with low coolant and the sensor is at the forward point of the tank. Maybe you just need a top off of coolant?