BoilerFaultCodesWhat the manual says
Manufacturer manualCentral Heating NTC Fault
What causes this fault?
This fault occurs when the internal thermistor, which monitors the temperature of the water leaving the boiler, sends an incorrect signal or stops communicating entirely. The most common reason is that the sensor has degraded over time due to constant heating and cooling, or the electrical wiring connecting it to the main control board has developed a loose connection.
This fault is slightly more common in winter when the boiler is running at higher temperatures for longer periods, putting more thermal stress on the sensor.
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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Related fault codes
All 21 fault codes on the Promax HE Store
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