Your boiler is still working but cannot reach its full power, meaning your radiators might not get as hot as they should.

Reduced burner output

What causes this fault?

This fault occurs when the boiler's control system detects that the burner cannot maintain its regular intensity, forcing it to operate at a lower power level. The most common reason is that the boiler is struggling to accurately monitor or control the gas flow and flame strength required for full heat. While the boiler stays on, it cannot generate enough energy to satisfy high demands for heating or hot water.