the markings are pretty simple

120
--- =100
80
--- = 60
40

you should check the gauge with a resistor (search on this forum for the specific resistor value) - you stick it in the wiring of the temp sender of the engine and it should read exactly 100 degrees. If it doesnt your gauge is duff.

furthermore the temp sender is then decided to be duff or good with the help of an infrared thermometer and a multimeter to verify the resistance/temperature reading.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)