combi boiler fault

I have the Combi E boiler and the Truma CP plus controller. For the second time I have had the warning code W45h which results in no space heating or water heating when connected  to mains. This time it occurred mid cycle and I was lucky to observe it.  The first time marquise diagnosed a faulty card which seemed to resolve the problem but the van is only 18 months old and I smell a deeper problem.  I have always worked on the idea of cause and effect with the card being the effect but what could be the cause.  Has anyone had this problem please and what rectified it
Gef

So now 18 months after the original fault I have managed to get some action from Marquise.  I had been fobbed of on several occasions and all the time they had a plug in fault finder they had not bothered to use.  Now in 5 mins all the fault codes are displayed leaving a clear list of spares to resolve the issue. So insist if you have a truma problem that they plug in the fault finder. I live in hope I may have a working van
Gef

Marquis surpass themselves once again!