Worcester 24i Junior Boiler - Hot Water Fine - NO HEATING?

Hi i recently moved into a house which has a Worcester 24i Junior boiler.

Hot water is fine but the heating does not come on.

Upon investigation it appears that when i activate the heating the boiler fires up, fan kicks in then the fan stops and boiler ticks off and error light flashes red.

Any ideas as i am struggling to find any answers on the internet.

The boiler was serviced in January so assume all worked then.

Any solutions would be appreciated

Thanks