Intermittent fault on biker mynute VHE

[Aire]

Couple weeks ago I was called to a customer complaining her hot water was extremely hot. When checking the system I found the 3 port to be stuck in the mid position which explained the hot water issue. While I was there I noticed the pump was an old bronze pump so advised it would be a good idea to also replace which she agreed. So new pump, new 3 port. System drained and filled up fine. Old pump was a little mucky but nothing out the ordinary for it age. House is only a small 3 bed with 7 rads. After running the system, everything worked fine. Customer has since contacted me explaining the boiler has needed resetting 3 times. Fault code flashing 74 which points to no water circulation. She also mentioned this had happened a couple times before my first visit so is an existing problem.
The boiler manual is a little vague as it just says check system operation, check pump and check water is in the system. I know these are fine so any ideas on what could be causing the fault?

 

[Last Plumber]

Is the pump wired from the boiler?
Is there a flow sensor on this boiler and if there is have you checked its function?
Is this a Vokera? It says biker on the title so I presume that’s predictive spelling?

 

[Aire]

Haha yes just realised that, stupid predictive texting. It is a vokera. I haven't checked anything in the way of sensors as I haven't checked the boiler over. I cant get back to the boiler till mid next week so ive just told the customer to reset for now. The pump is wired into a wiring centre but had overrun so is linked to the boiler.

 

[Last Plumber]

Haha yes just realised that, stupid predictive texting. It is a vokera. I haven't checked anything in the way of sensors as I haven't checked the boiler over. I cant get back to the boiler till mid next week so ive just told the customer to reset for now. The pump is wired into a wiring centre but had overrun so is linked to the boiler.

Is it this one?

 

[Aire]

Is it this one?

Yes that's the one.

 

[Last Plumber]

Yes that's the one.

I would start by checking how the pump is wired and looking at the flow sensor?
Don't do much with Vokera personally but that's where I would start.

 

[Aire]

Tu

I would start by checking how the pump is wired and looking at the flow sensor?
Don't do much with Vokera personally but that's where I would start.

I don't do much with any boiler in terms of repair, I'll probably give vokera a call on Monday. Chances are when I go look at the boiler it will be after hours so hope they can give me some pointers before I turn up