BoilerFaultCodesTechnical description
Adjust CO2. Set the CO2 content.
What causes this fault?
This fault occurs when the boiler's sensors detect an incorrect mixture of gas and air during the combustion process, meaning the flame is not burning as it should. The most common reasons are a drifting gas valve that needs recalibration or worn-out spark electrodes that are struggling to ignite the gas cleanly. In some cases, it can be caused by a fault in the main control board failing to manage the gas flow accurately.
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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