D.40 Low
Your boiler is displaying its current target temperature and is working normally, as this is an information status code rather than a fault.
Technical description: Flow temperature target value
Typical repair cost: £0 (including labour)
DIY fix possible
No action is required as this is an informative status code.Check that your external thermostat or programmer is set to the desired temperature.Bly observe the display; it should change once the target temperature is reached or adjusted.
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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