Blinking centre diff light.. 18 plate, Barbarian Auto, 97k .

My centre diff (I think!) light has started flashing when I drive on a motorway. It doesn’t appear to be temperature related as, when I turn the engine off and back on again, it goes away for 10-15 minutes.

Truck was bought in December and has been fine until yesterday. Driven on motorways once or twice a week, drives on farm tracks/off road daily, and 4wd has been engaged at least once per week since purchase.

I’m assuming some sort of sensor fault but which one/where do I look/start? And if you can explain in very easy terms I would very much appreciated it (my knowledge of engines went with my old polo about 20 years ago!).

Many many thanks in advance 😊