BoilerFaultCodesYour boiler is currently running at its highest power level for testing purposes and is not indicating a system failure.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Boiler is operating at maximum load (Test program 'H')
What causes this fault?
This code appears because the boiler has been manually put into a high-power test mode, usually by an engineer during a service or installation. It indicates that the burner is firing at its maximum capacity to check performance and gas pressures. It is a status indicator rather than a mechanical failure or a broken part.
This code is most common during the autumn or whenever you book your annual boiler safety check, as engineers use this mode to test the appliance.
DIY fix possible
Press the '+' and '-' buttons simultaneously to exit the test modeSwitch the boiler off and back on at the main fused spur switchWait for the boiler to complete its cycle and return to its normal temperature display
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A boiler cover plan would cover faults like HH — no call-out fees, no surprises.
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