Main eco30 combi error 83 communication error

[Teddy2018]

Hi all. Looking for some help pls. I have a main compact eco30 boiler.
The display flashes on and off with E83.
When I look this up, it means COMMUNICATION ERROR. There is also a spanner flashing. The boiler runs continuously and can only be switched off at the wall, instead of being controlled by the thermostat.
When this happened I noticed that there was no power to my wireless thermostat controller.
As I thought this was the problem, I replaced for a new salus unit, and there is now power at the unit.
Unfortunately, I still have no control over my boiler, ie On/Off. It will run constantly, unless I manually switch off at the wall.
E83 flashes constantly, and I cannot reset. Have read manual, but no details are given regarding this error code.
Is this a PCB problem? Are there any internal fuses I can check? Does anyone know how to reset this?
Has any one else had this problem? If so, what was the resolution? Please help. Thank you in advance.

 

[jj4091]

Is your controller supplied electrically by an idependant FCU near the boiler or directly from the boiler

 

[Teddy2018]

Hi there, my controller gets it's power directly from the boiler.

 

[RandomGrinch]

OK, there is a slight distinction - I believe you have a "Main Eco Compact Combi 30".
Error 83 would relate to a communication error to an OpenTherm thermostat.
If the previous stat had failed (and was OT) you would get a communication error - if the new stat was not an OpenTherm stat, the default behaviour is to keep the heating turned on, if the OT terminals are connected.
What model was your old thermostat, and what is your new one?
Can you also post a picture of how you have connected it up?