2010 Ford focus Zetec 1.6 Diesel U0073 DTC

I’ve had my 2010 Ford Focus Zetec 1.6 TDCi for a week now.

There is the DTC U0073 (control module communication Bus ‘A’ off) on it.

There is no issues with the car,no warning lights on dash, drive is smooth and I can’t complain apart from it maybe pulling to the left a bit(my first car so all new too me).

At the start it did flash up with the seatbelt warning light but that has since stopped. I have the Haynes manual(2009 model) for the wiring diagrams but where/what is Bus ‘A’ in this car? I have a little understanding of the principles of the can bus system.

I have cleared the DTC but it has come back so seems like a persistant issue.

Any help/ideas appreciated. Cheers