What does the Vaillant F.20 fault code mean?

Your boiler has switched itself off because it has reached an internal temperature that is too high, often caused by a blockage or poor water flow.

How much does it cost to fix Vaillant error code F.20?

Typical repair cost for the Vaillant F.20 fault is £120-£350 including labour.

Check that all radiator valves are fully open

Over heat cut off activated | Maximun temperature exeeded

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

Each noise points to a different fault.

Work through these before the call-out.

Lockout fault with a reset-needed pattern.