2003 X5 3.0

Every new yorkers nightmare, getting stuck in the lincoln tunnel. Luckily the coolant temp warning came out just as I was getting out of the tunnel. I then pulled over and shut the car off right away. I got out and looked in the engine bay, no coolant leak, nothing smoking. I got back in the car, turned it on and went to see if the large radiator fan was turning, it was - so i got back in the car and watch the temp sensor go right back to the middle, exactly where it always is for 16 years. Car then drove fine for next 15 minutes, I parked it, then drove again another 15 and then another 15. No more issues.

So - any suggestion on what is going wrong here... thermostat was replace already by me, a few years ago. Do you think the water pump is going? Could it be the big fan control? I have not replace the hoses, but they look okay, nothing looks crushed (but I think there are some hoses that run under the exhaust manifold that I cannot see).

Thanks. Definitely need this sorted out. Can't risk getting stuck!

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2003 X5 3.0i Silver (build 07/03)
2006 X5 3.0i Blue
1977 Ferrari 308 GTB
1994 Ferrari 348TS Speciale #14/15
1989 Ferrari Testarossa