Your boiler is having trouble communicating with an internal connection module, which means it cannot properly coordinate its heating and hot water functions.

Control mode Incorrect LON communication module

What causes this fault?

This fault occurs when the boiler’s automated filling system becomes stuck or fails to complete its cycle, often because the system cannot reach the required pressure. The most common reason is a manual filling valve being left open by mistake or a malfunction in the electronic sensor that monitors the water level. In some cases, the internal control board may be unable to register that the filling process has finished, causing the boiler to halt for safety.