This could be a wheel speed sensor fault or possibly an abs module problem.The speedo works from the abs system.A dignostic test will give an idea as to the problem area.It is not a specific fault with Ford models as lots of other manufacturers use the same ATE abs system.hth

From regular fault diagnostics with these linked failings,it is normally the dash cluster at fault..canbus errors are logged in the ABS and Engine control system as bus error and comms failure to read abs and engine and vice versa..BBA Reman can repair it a new one is £217.plus vat and an hours labour to reinstate it.