What the manual says
Manufacturer manualTemporary fault code (Refer to section 7.10)
What causes this fault?
This fault occurs when the boiler's internal electronics detect a brief interruption or a glitch in the data being sent between sensors. The most common cause is a sensor that is starting to wear out or a small electrical disturbance on the main control board that makes the system pause to re-check its readings.
DIY fix possible
Monitor the boiler to see if the code clears automaticallyPress the reset button if the code remains or turns into a lockoutEnsure power to the boiler has not been interrupted or fluctuated
Avoid the next call-out bill
A cover plan would handle faults like 40: no call-out fees, no surprise bills.
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