BoilerFaultCodesWhat the manual says
Manufacturer manualCheck HW sensor/lead. Sensor may have failed 'low resistance'.
What causes this fault?
This fault occurs when the boiler's internal computer receives an incorrect electrical signal from the hot water temperature sensor. It usually means the sensor has developed a short circuit or the wiring connecting it to the main control board has become damaged or loose. Because the boiler no longer knows how hot the water is, it shuts down as a safety precaution to prevent overheating.
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 HW light on PCB 40 flashing: no call-out fees, no surprise bills.
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