What does the Vaillant D.50 fault code mean?

Your boiler is struggling to calibrate the internal fan speed required for safe and efficient combustion.

How much does it cost to fix Vaillant error code D.50?

Typical repair cost for the Vaillant D.50 fault is £150-300 including labour.

Manufacturer manual

Offsetforminimumspeed

From this model's manual

Verified against the Vaillant/Vaillant Ecotec 65kw installation & service manual, page 32.

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.50: no call-out fees, no surprise bills.

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

Each noise points to a different fault.

Safety-critical — turn off, read this.

7 signs repair isn't worth it anymore.