i keep getting fault code f75 on my vaillant ecotec pro 28?

Ok spoke to a plumber. turns out in my case it is the water pressure sensor. it was removed & there was a lot of black gunk in the hole at the base of the sensor. it was cleaned out & a thin screwdriver pushed in the hole against the internal spring. rinsed with warm water, tapped onto a chopping board to dislodge any more gunk, rinsed again then replaced. system refilled with water & it all works now

si1968
December 2009

i keep getting this fault. the pump is working & the pressure is 1.5bar. whatis the expansion vessel?

si1968
December 2009

assuming Vaillant use the same fault codes across the ecoTEC range book says
F75 = no pressure rise was detected on turning on the pump.
Causes.
water pressure sensor or/and pump defective
air in the heating system, quick bleeder defective.
too little water in appliance,check adjustable bypass,connect external expansion vessel to return


my F 75 fault turned out to be a (flat expansion vessel),

wirecutterman
December 2009