BoilerFaultCodesWhat the manual says
Manufacturer manualNTC3 short-circuited (NTC3 = sensor on the storage heater) Storage heater probe short-circuited
What causes this fault?
This fault occurs when the boiler's internal components reach an unsafe temperature, triggering a complete shutdown to prevent damage. The most common reasons are a failure in the water circulation system, such as a faulty pump, or a defective sensor that is incorrectly reporting the heat levels to the control board.
This issue is more frequent during the first cold snap of winter when heating systems are suddenly pushed to run at high temperatures after being idle for months.
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 E20: no call-out fees, no surprise bills.
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