Any advice to troubleshoot blank screen on boiler?

[Kingerna1]

Hello. Wondering if anyone can throw a tip or two my way on where to look on why my boiler had a blank screen. It has happened in the past and it was a fuse but i did check all fuses and they all tested good. There is power coming into the boiler but thats it? Low water cutoff is good as well. Its a vitodens 100w Thanks for any help!

 

[ShaunCorbs]

You have 120v coming into the boiler correct?

 

[Kingerna1]

You have 120v coming into the boiler correct?

Yes there is 120v coming in to the controller but no power to the circulating pump. I have been cycling it on off a few times etc and got the screen to come on. one it displayed an E3 code then went blank. Then the next time it displayed an FD code.

E3

204

Burner in fault mode

Heat transfer too low during calibration. Temperature limiter caused shutdown.

Ensure adequate heat transfer. Press reset button R.

FD

227

Burner in a fault state and additional fault B7 is displayed

Boiler coding card is missing

Insert the boiler coding card. Press reset button R. Replace control unit if fault persists.

So very confusing

 

[Kingerna1]

Yes there is 120v coming in to the controller but no power to the circulating pump. I have been cycling it on off a few times etc and got the screen to come on. one it displayed an E3 code then went blank. Then the next time it displayed an FD code.

E3

204

Burner in fault mode

Heat transfer too low during calibration. Temperature limiter caused shutdown.

Ensure adequate heat transfer. Press reset button R.

FD

227

Burner in a fault state and additional fault B7 is displayed

Boiler coding card is missing

Insert the boiler coding card. Press reset button R. Replace control unit if fault persists.

So very confusing

Another explanation for FD
All Viessmann boilers
Burner control unit in a fault state; system cools down; burner control unit locked out
Short circuit – Boiler water temperature sensor, burner control unit

 

[Kingerna1]

Another explanation for FD
All Viessmann boilers
Burner control unit in a fault state; system cools down; burner control unit locked out
Short circuit – Boiler water temperature sensor, burner control unit

Not sure why I get different explanations for the code FD but here is another out of the manual
FD-Burner blocked Burner control unit fault Check ignition electrodes and connecting cables. Check whether a strong interference (EMC) field exists near the equipment (correct if applicable). Reset control. Replace control unit if the fault

Maybe the control unit? Thanks again!