Biasi - Error 14?

[xd400]

From what I've read this is possibly a pump failure but not sure. Could it be something else?
Tap hot water comes out then cools...heats again....cools and then boiler goes into error 14.

Boiler is a Biasi Advance 30C 30KW Combi.

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[terryplumb]

Blocked plate heat exchanger probably.

 

[CBW]

Pump or temp above 105 degrees C according to the manual, so could be blocked heat exchanger.

 

[xd400]

Thanks. Previous boiler's DHW exchanger used to get clogged too. System was flushed and always has a Magnaclean on the return. Will take a look.