BoilerFaultCodes dd Medium Warning
Your boiler has lost connection with the indoor temperature sensor that controls your main heating, meaning it cannot accurately tell how warm your home is.
Book a service
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: Room temperature sensor heating circuit A1 lead break
What causes this fault?
This fault occurs when the electrical connection between the boiler and your indoor thermostat is interrupted. The most common reasons are a loose wire in the back of the sensor, a break in the cable running through your home, or a failure of the internal sensor component itself.
Typical repair cost £100-£220 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A boiler cover plan would cover faults like dd — no call-out fees, no surprises.
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