What does the Vaillant F.75 fault code mean?

Your boiler is unable to confirm that water is moving around the system because it cannot detect a change in pressure when the internal pump starts.

How much does it cost to fix Vaillant error code F.75?

Typical repair cost for the Vaillant F.75 fault is £150-350 including labour.

No pressure change detected when starting the pump

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

Six most common causes of dropping pressure.

Each noise points to a different fault.

Safety-critical — turn off, read this.