What does the Vaillant D.30 fault code mean?

Your boiler is failing to light because the main control board is not sending the necessary signal to open the gas supply valves.

How much does it cost to fix Vaillant error code D.30?

Typical repair cost for the Vaillant D.30 fault is £180-450 including labour.

Control signal for both gas valves

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

Older boilers — thermocouple, draught, gas supply.

Safety-critical — turn off, read this.

7 signs repair isn't worth it anymore.