If the temp dropped right back to "noon" then you may have just had an occurrence of a known bug in the DME that will randomly set the temp needle to max.

It happened to me once. I pulled over and put my hand on the radiator hose without difficulty I knew it wasn't actually overheating so I figured was a bad sensor.

Turned the car off and back on and needle went back to normal.

The dial on the dash is not a proper gauge. It for all intents and purposes is a three position idiot light:

Cool, normalish, overheated.

I'm willing to bet your case was like mine.

Use the hidden menu to monitor ECT (engine core temp) to confirm the cooling system is behaving properly.

I think it might be test 7. It will show the engine temp in °C

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)