While you wait for answers, we may have found some information which could help you.
Click here for Working Fine LightVailliant turbo max plus 824e?
Vaillant ecotec 831 plus?
how do I rectify the fault as detailed below?
Vaillant VCW-Sine18 T3WFH Lights but then goes off after 5 Min?
Vaillant condensing boiler ecoTEC plus?
how to fix water pressure its down at bottom of grey part?