What does the Vaillant S.33 fault code mean?

Your boiler is temporarily pausing because its internal safety sensors detect that the airflow needed to burn fuel safely is not moving correctly.

How much does it cost to fix Vaillant error code S.33?

Typical repair cost for the Vaillant S.33 fault is £150-300 including labour.

Waiting time: Air monitor (Waiting period: Air pressure sensor/switch reports that the pressure signal is too low)

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.