Vaillant ecotec plus. s75 code?

My sister always turns her boiler off and in doing so, the pressure drops, you can connect a silver flexi pipe (which should be under your boiler usually hanging over the pipes) to connect the valves underneath, then slowly open both and the pressure will rise. Be careful to only raise it slightly as when it is in use the pressure will build up and shouldn't be above the line guide.

Karl
January 2022

F75 (not s75) relates to one of two things:
System pressure switch not functioning (often due to dirt in the system)
or:
Problem with the pump.

Most likely, pressure switch especially if it's a salmon pink colour.

Carefree
November 2010