What does the Vaillant F.86 fault code mean?

Your boiler has detected that a safety sensor meant to prevent underfloor heating pipes from overheating is not sending a signal or is disconnected.

How much does it cost to fix Vaillant error code F.86?

Typical repair cost for the Vaillant F.86 fault is £120-250 including labour.

Fault:Underfloorheatingcontact | Underfloorheatingcontactopen,sensordisconnectedordefective

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Lockout fault with a reset-needed pattern.

Safety-critical — turn off, read this.

Break-even maths on monthly cover.