We may have found other answers which could help you.
Click here for Vaillant 242 Boilerhow to fix water pressure its down at bottom of grey part?
Vaillant VCW-Sine18 T3WFH Lights but then goes off after 5 Min?
Vaillant ecotec 831 plus?
vaillant ecoTEC plus boiler fault code - how to fix?
What does f.25 mean?
Vaillant eco plus 531 boiler?