Your boiler has detected a temporary technical issue that frequently relates to an internal communication error or a sensor detecting an unusual reading.

Temporary fault code (Refer to section 7.10)

What causes this fault?

This fault occurs when the boiler's internal computer experiences a momentary communication glitch or receives an inconsistent reading from one of the temperature sensors. It acts like a temporary digital 'hiccup' where the main control board becomes briefly confused by the data it is receiving. If the issue persists, it usually points to a failing electronic control board or a sensor that is starting to wear out.