Your boiler is experiencing a temporary communication or sensor error that may resolve itself but often indicates a part is beginning to fail.

Temporary fault code (Refer to section 7.10)

What causes this fault?

This fault occurs when the boiler's internal computer receives an inconsistent or 'noisy' signal from its sensors, causing temporary confusion in its operation. The most common reason is a sensor that is starting to provide inaccurate readings or a minor electrical glitch within the main control board's communication circuit.