D.90 Low
Your boiler is currently waiting for a signal from an external smart control or thermostat, meaning it is in a standby or communication phase rather than a fault.
Technical description: Digital regulator status
Typical repair cost: £0-120 (including labour)
DIY fix possible
Check that your room thermostat is turned up higher than the current room temperatureEnsure your external heating programmer is set to 'ON' or 'AUTO'Check the batteries in your wireless thermostat or smart controller
Protect yourself from future repair bills
A boiler cover plan would cover faults like D.90 — no call-out fees, no surprises.
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Parts commonly replaced
- Thermostat batteries
- External heating controller
- eBUS communication cable
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