Vokera Compact HE Combi NTC Fault?

On a Vokera Compact HE Combi boiler would these symptoms very likely be a faulty thermosensor? - Boiler appears fine and CH works fine - When CH is on and u need hot water the water is heated but cuts after few minutes and indicated red LED and needs reset - reset fine and maybe fine for few minutes then same again - Yet is just hot water required and CH is off it lasts for ages then maybe just maybe cuts out - The red LED indication in book is lidted as a NTC sensor being the cause of a shut down (water is NOT overheating) I can source these parts easily - would anyone say its very likely simply a faulty sensor of the two NTC fitted? I would - just need a reliable opinion - HELP! Thanks