We may have found other answers which could help you.
Click here for Intermittent Heating FaultVaillant condensing boiler ecoTEC plus?
Vailliant turbo max plus 824e?
Problem with the pressure in combi boiler?
Vaillant ecotec 831 plus?
Vaillant eco plus 531 boiler?
Vaillant VCW-Sine18 T3WFH Lights but then goes off after 5 Min?