High Lockout
H.02 – .04 on Baxi 200 Combi (range)

Your boiler's computer brain is momentarily confused by some internal settings and cannot operate correctly.

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

Temporary error- parameter fault. Incorrect parameters.

What causes this fault?

This fault occurs when the boiler's main control board loses its specific configuration settings or detects a mismatch in its internal programming memory. It is often triggered by a sudden electrical surge, a failing memory chip, or a breakdown in the communication between the boiler's internal components. Because the boiler no longer knows its own operating limits or model type, it shuts down as a safety precaution.

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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