BoilerFaultCodesWhat the manual says
Manufacturer manualService function
What causes this fault?
This status occurs because the boiler has been manually put into 'Service Mode' using the internal control selectors. It is physically triggered when the mode selector dial is turned to the specific testing position, usually to allow an engineer to measure gas pressures without the boiler modulating. It is not a component failure, but rather a sign that a manual override is currently active.
DIY fix possible
Check if the mode selector dial has been left in the 'Service' or 'Chimney' position.Turn the selector dial to the 'OFF' position for 30 seconds.Turn the selector dial back to your desired 'Hot Water' or 'Heating' setting to resume normal operation.
Avoid the next call-out bill
A cover plan would handle faults like Yellow | On every 0.5 second: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.