Thanks for the help.
Yes I assume it's the latter as the ABS light is on too. But have no idea how to scan the ABS. Is this something I can do with my code reader?
Is there any trick to find out which sensor is faulty? I assume I just need to take each one off in turn and measure the resistance through it?

I was assuming/ hoping the throttle sensor reading was also based on same problem, but one thing at a time I guess. Once (or if) I get the ABS and speedo sorted, I can move on to throttle would seem like a plan!
Thanks
Graham