BoilerFaultCodesTechnical description
Fault U: Network CodeProblem is climate control system, lighting, airbags, etc..fault two; MFG – Manufacturer Specificfault four; Transmissionfault five; TP Sensor Learn Not Completefault three; Transmission Control Module Reprogrammable Memory
What causes this fault?
This fault occurs when the boiler's internal electronic brain suffers a data failure, meaning the different components can no longer talk to each other reliably. It is usually caused by a physical hardware failure within the circuit board or a corruption of the stored settings that dictate how the boiler should operate. Without this internal communication, the system shuts down as a safety precaution to avoid running blindly.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.