BoilerFaultCodesWhat the manual says
Manufacturer manualMaximum setting of heater control knob
What causes this fault?
This code appears when the heating temperature dial or digital control has been turned up to its highest possible setting. It occurs because the boiler is being instructed to deliver its maximum heat output to the radiators, often after someone has manually adjusted the controls for more warmth. It is a status indicator rather than a broken part.
This is more common during extreme cold snaps in winter when homeowners turn their thermostat or boiler dial to the maximum setting to combat the freezing weather.
DIY fix possible
Locate the heating control knob on the front of the boiler panel (marked with a radiator icon).Turn the knob slightly to the left to reduce the target temperature to a more efficient level (e.g., 65-70°C).Observe the display to ensure the temperature setting has updated.
Avoid the next call-out bill
A cover plan would handle faults like D.71: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
All 135 fault codes on the ecoTEC plus 612 R1 VU GB 126/3-5
Seeing a different code? Every code this model can display, in one place.