I had this on my 19 outlander over the weekend on a trip up North once past Stevenage, which was annoying.
However, yesterday all was working but in the evening gone again.
Then I remembered something I had with my Galaxy ages ago and it turns out the cigarette lighter phone charger I had to buy on my trip because the kids forgot to charge their phones, was causing it when a phone was plugged in.
Definitely the charger.
Steve