BoilerFaultCodesWhat the manual says
Manufacturer manualTemperature safety sensor above 101 °C.
What causes this fault?
This fault occurs when the water inside the heat exchanger becomes too hot, causing the safety sensors to shut the system down to prevent damage. The most common reasons are a failed pump that isn't moving water away from the boiler quickly enough or a blockage in the pipework restricting flow. It can also be caused by a build-up of air or a faulty sensor sending an incorrect temperature reading to the control board.
This issue is more common during the first cold spell of autumn, when pumps that have been idle all summer can seize up or struggle to restart.
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.
Avoid the next call-out bill
A cover plan would handle faults like 4F: no call-out fees, no surprise bills.
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