What does the Vaillant d.35 fault code mean?

Your boiler is struggling to switch between heating your radiators and providing hot water to your taps.

How much does it cost to fix Vaillant error code d.35?

Typical repair cost for the Vaillant d.35 fault is £180-350 including labour.

Manufacturer manual

Position of the diverter valve

Shared across the ecoFIT Pure 830 range

This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Boiler cover options

A cover plan would handle faults like d.35: no call-out fees, no surprise bills.

Approved partner

Domestic Appliance Guard

Unlimited call-outs, 24/7 helpline, no price-hike promise

Affiliate links. We may earn a commission at no extra cost to you.

Seeing a different code? Every code this model can display, in one place.

Almost always a stuck diverter valve on a combi.

One cold radiator is usually a stuck valve pin or trapped air.

On a combi it is usually the diverter valve. On a system boiler, the motorised valve.