Weird problem - no start, showing -40*F

[oldskewel]

Weird problem today, trying to start my 2001 3.0i with 183k miles, running well ...

Turning the key just gave click-click-click (loud, stong clicks). No actual attempt for the starter to turn. No start.

Repeated this at least twice. Maybe 3 times with the same result.

Weird. I figured someone had left a light on and run down the battery, so I searched, did not find anything. Checked battery voltage at the jump points in the engine bay, with a voltmeter = 11.7V = plenty good to start.

Back in the seat, the green LED for the AC was on, so I pushed the AC button to turn that off. Turned off all HVAC controls too. Turned off the computer screen thing.

Tried again and it started right up, everything looking great except it tells me the temp is -40*F. Idles fine. Shut it down, restarts just fine, still thinks it's -40*F.

My son then wanted to borrow it for a ~10 mile round trip to go running (yes, drive 10 miles so he can run 10 miles in the hills; so I figured if the car stranded him, he could just run a little further). When he came back, he told me the temp was displaying as -37*F.

No problems at all before this. Nothing weird.

Any ideas? I am pretty certain the -40*F is related to the failed start.

BTW, it was probably about +60*F at the time.

Thanks!