Your boiler has temporarily paused operation because it has detected very cold temperatures or an unusual fluctuation in the fan speed, often caused by strong winds or a blocked flue.

Antifreeze active – fan speed variation too high – waiting during blocking function

What causes this fault?

This code appears when the boiler's internal sensors detect that the fan speed is fluctuating too much or that temperatures have dropped near freezing. This usually happens because strong winds are blowing back down the flue pipe or there is a physical restriction, such as ice or debris, causing the fan to struggle to maintain a steady speed. The boiler pauses briefly as a safety measure to protect the components from freezing or incorrect combustion.