Worcester CDI U Codes

[Kewat66]

Hi All,
i have been working on a Worcester 35 CDI. The boiler wasn't getting the heat away and was going up to 99 on the screen and then going into u codes. Nothing in the manual on these but having changed the pump, diverter motor & temp sensor the boiler worked for a week then started playing up again. The new pump had failed so was changed again but the original problem is still happening albeit not as often. Worcester have said to change the board but not sure about this. Does anyone no about these u codes and has anyone had a similar problem?
thanks
kewat66

 

[Atouchofgas]

Means uber in German which means it's overheating ie over 99

 

[gassafe]

2 digit display... It goes to U to indicate over 100 degrees... Eg u9 is 109

 

[gastec]

Hello i have had the same issue before when running hot water, just cleaned out the plate heat exchanger and its been fine since. You do not need a new pcb at £200.

 

[Kewat66]

Thanks I will give this ago ad see what happens