We may have found other answers which could help you.
Click here for Vaillant Vuw TurbomaxVaillant 828E - no hot water?
Hot water comes and goes!?
vaillant ecoTEC plus boiler fault code - how to fix?
how do I rectify the fault as detailed below?
Vaillant condensing boiler ecoTEC plus?
Vaillant ecotec 831 plus?