Watch this video HOW to test a boiler / PCB Before any work is done on any boiler you should do this 4 Part test. Our yellow (easy to follow) FAULTS...
VAILLANT ECOTEC PLUS 824 831 837 & ECOTEC PRO 24 28 CIRCUIT BOARD PCB 0020132764 | eBay
Vaillant PCB EcoTec Plus : Amazon.co.uk: DIY & Tools