Sorry that I haven't replied in a few days was waiting for the sensor to show up !!
I have not changed the heater element
I changed the 1 sensor that came in and i still ended up with an SNS code after a short while
It Ran for at least an hour and I got the OHH code again
Jets weren't doing any funny things
The circulation pump is definetly circulating water, but from what I remember when the heater element is on, isn't the circulation pump supposed to speed up from an "idle"?
Thanks so much for your replies really appreciate the help