BoilerFaultCodesTechnical description
Ion control deviation is too big – try resetting the boiler
What causes this fault?
This fault happens when the boiler's internal sensor detects that the flame is burning inconsistently or not matching the expected safety signals. It is often caused by a worn-out sensing probe that can no longer 'see' the flame clearly, or a gas valve that is failing to deliver the correct amount of fuel to keep the burner stable.
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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