What does the Vaillant F.00 / F.0 fault code mean?

Your boiler has lost connection with the internal thermometer that monitors water temperature, causing the system to shut down for safety.

How much does it cost to fix Vaillant error code F.00 / F.0?

Typical repair cost for the Vaillant F.00 / F.0 fault is £90-160 including labour.

Flow temperature sensor interruption

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

Almost always a stuck diverter valve on combis.

Safety-critical — turn off, read this.

7 signs repair isn't worth it anymore.