Sensor alert sounds as soon as I reach 10mph then an error message is displayed stating sensors need a service. Any ideas?

Is the message definitely for parking sensors?  Can't think of any reason they'd trigger a warning at exactly 10mph.

Do you have active park assist, where the car can park itself?  Or just park pilot with the sounds and radar display on the screen?  Rear only or front & rear?

Thanks for the reply.

It's a 2013 Grand Cmax, with rear sensors, no cameras, auto parking or a large screen. The car starts up and whilst stationary does not display a message. When I move off or select reverse and not move, the message is displayed. Due to illness, the car has not been used very much over the past two months. I have now started to use it more and the error message has started to appear. The error message disappears after a few seconds leaving an "INF" on the small info screen.

Ok.  I can't recall seeing that message before.

I suspect some damp has got into a plug or the park assist module (PAM) while it was parked.

I don't think it'll be an individual sensor fault.  Would expect different symptoms for that.

Think I'd look for the PAM module (in the boot) and check for any signs of water ingress around it or any corrosion on the plug pins.