High Lockout
H.03 – .01 on Baxi 200 Combi (range)

Your boiler's computer parts are having trouble talking to each other, which means the system cannot operate for heating or hot water.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Communication error with the printed circuit board (PCB)

What causes this fault?

This fault occurs when the boiler's internal control board loses its connection with the sensors and valves that regulate heating. The most common reasons are a loose internal wire connection, moisture getting onto the electronics, or a component failure within the circuit board itself.

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.

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