BoilerFaultCodesWhat the manual says
Manufacturer manualAppears if the burner thermostat has been activated.
From this model's manual
Verified against the Vokera Synergy E installation & service manual, page 53.
What causes this fault?
This fault occurs when a safety sensor near the burner detects that the internal temperature has exceeded safe limits, causing the boiler to shut down to prevent damage. The most common reason is a build-up of debris or limescale inside the heat exchanger which restricts water flow, but it can also be caused by a faulty sensor or a pump failure.
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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