vaillant water pressure sensor replacement f73 f75 error eco-tec pro 

amzn.to/3II1MjG - link to expansion vessel charger - after having a couple of people ask.
this is NOT the only cause of this fault code... just a common one. others include pump, low pressure, blockages, filter issues, potentially expansion vessel problems.... (non exhaustive...) The point of the video is to show how to replace a water pressure sensor - which is a fairly common fault. it should be done by a gas safe reg'd person.