Baxi 7688421 Combi/System PCB Kit

The Baxi 7688421 is a printed circuit board kit intended for combi and system boilers. It sits within the boiler's electronics and controls group and carries the control logic that governs operating sequences, temperature regulation, pump and fan demand, and fault monitoring. It is supplied by Baxi as a single kit.

• The boiler fails to fire or repeatedly drops into lockout with no mechanical cause found.
• No heating or hot water is produced even though there is a call for heat at the thermostat or a hot tap.
• The display is blank or unresponsive, or fault codes return immediately after a reset.
• The pump, fan or diverter is not driven when the boiler is called to run.
• Operation is intermittent, with the appliance cutting out and restarting at random.

• Confirm the boiler model, GC number and serial number against the compatibility list.
• Check that the part number printed on the existing board matches 7688421 before ordering.
• Isolate the electrical supply and follow the manufacturer's wiring and configuration instructions when fitting the replacement.