Hmm...
Afraid I can't really help much.
But I'd check the wiring to the temp sensor, on my 460 Turbo it had broken where it enters the plug.
Apart from that, a sensor is reasonably cheap and easy to change, so I'd give it a go
Good luck!
Steve
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XC90 V8 Exec, C70 2.4T Convertible, S70 T5 CD, 850 TDI, 2 x Escort vans and a 2.8i Capri.
Clearout has begun, but must continue!