what is an error code po500 please

That is a VSS (vehicle speed sensor) fault.

As with all error codes you should make a note of the code then reset it. Only if the same code returns should you start doing anything else.

Vehicle electronic control units are like all other computers, sometimes they give spurious error messages and need to be reset or re-booted. Often the fault will not reappear so only take action if the same message comes up again.

Good luck.

Am I the only person on the forum who sometimes gets a bit annoyed when people can't be bothered to say thanks for the help and interest with their problem?

Having gone to the trouble of replying to their query, sometimes even getting the books out to check facts, the least they could do is say 'thanks'. The forum even makes it easy for them by providing a 'Thanks' button to click on at the bottom of the window!

There you go, rant over! Have a great day everyone.