Great info, thanks to all. Appears in a MAP thermostat the heating element receives power from the DME before 110C allowing it to open, which is good for faster heater operation. And a MAP thermostat heating element also receives power above 113C to allow the engine to run cooler, apparently by opening the thermostat further allowing more coolant flow. (A very complex and expensive solution to achieve incremental emission and gas mileage gains over a simple 85C thermostat).

As the previous poster noted, this thing can be intermittently receiving power and cycling multiple times on any trip, but particularly so when occasionally running the engine harder and with more frequent short trips. I don’t run the engine hard but I do have frequent short trips, making the early demise of the secondary function make sense. Now I don’t feel bad about having it replaced and in fact want to replace it, and moreover I don’t think I need to replace the water pump. And it’s also worthwhile to ensure something isn’t causing the engine to run hotter, although my thought is an old vehicle with corroded channels in the engine, heater and radiator is the most likely culprit. Can anything be done about that except replace thermostat and flush coolant which I plan to do? I would not use any additives, but do the dealers use a flush that can dissolve some of the corrosion?

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'03 4.4 M62
Original Owner 107k on the clock
Alpine White/Beige Leather

Others:
2013 M-B E350 S4 Touring
2016 M-B E350 S4 Touring
2004 Porsche 911 C4S Track Duty