Your boiler is struggling to accurately check the quality of its exhaust gases, which is preventing it from completing its ignition cycle safely.

Flue gas measurement not possible. Flue gas analysis is not currently possible.

What causes this fault?

This fault occurs when the boiler's internal sensors fail to accurately measure the combustion gases during the startup phase. It is often caused by a faulty gas valve or worn electrodes failing to produce a stable flame that the system can verify. Without a reliable reading of these exhaust gases, the boiler enters a safety mode to prevent inefficient or dangerous operation.