D.40 Low
Your boiler is displaying the temperature it is currently aiming for rather than a fault, which is a normal status message and not a breakdown.
Technical description: Flow temperature target value
Typical repair cost: £0 (including labour)
DIY fix possible
Check if your thermostat or external controls are set higher than the current room temperatureWait for the boiler to complete its current heating cyclePress the 'i' button to exit the diagnostic information menu if you entered it accidentally
Protect yourself from future repair bills
A boiler cover plan would cover faults like D.40 — no call-out fees, no surprises.
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