Does the dashboard temp gauge use the same sensor as the DME computer. My temp gauge sits on 100°, the lowest reading, and never moves yet I can see normal temperature operation while viewing “live data” via my diagnostic tool.

 

Yes there is only one sensor. The Gauge pod on these cars is all digital, the ECU tells the gauges what to read via CAN messages. So if the gauge isn't moving it may be a bad dial.

Durametric pro or PWIS tool should be able to a sweep test to confirm.

 

It's not normal as mentioned - checking it with a gauge-cluster test is worth doing.

Understanding how it's supposed to work may help. The temperature gauge is an analog idiot light. It is not an actual gauge. It will show cold until a certain temperature is reached in the engine, then it will creep up to 180F/200F (some are higher than others). At that point, it will sit there dead center even as the engine temperature swings 20-25F. If the engine overheats it will start climbing, and it usually does this when it's already badly overheated when it swings into the red and lights up red. It will also light up red and post a message on the message section of the instrument cluster if the system determines coolant is low on the first cold startup. If you cycle the ignition that message normally goes away. Add coolant to the max mark when cold and it won't happen again until you've leaked enough coolant to make it actually low.

Yours sounds KAPUT - especially if you're seeing real temperatures with your DME computer.