Error code 31 for Worcester-Bosch Greenstar 30cdi conventional boiler?

Hi hopefully someone out ther can help/advise.

We have a new (just over a year old) boiler. I set the boiler to constant but nothing happened. The boiler is showing a code of 31 which I can't find any reference to in the manual. Is this the temp?

Nothing happens when I try to reset the boiler, it just reverts to "31" I have increased the setting on the thermostat to no avail.

Help