D4 271 High
Your boiler is overheating because water is not moving through the system quickly enough to carry heat away.
Technical description: Temperature difference between flow and safety sensor exceeds limit
Typical repair cost: £120-350 (including labour)
DIY fix possible
Check that all radiator valves are fully openCheck that the boiler pressure is between 1 and 1.5 bar on the pressure gaugeBleed all radiators to remove trapped air that might be blocking water flow
Protect yourself from future repair bills
A boiler cover plan would cover faults like D4 271 — no call-out fees, no surprises.
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Parts commonly replaced
- Circulation Pump
- Main Heat Exchanger (Descaling)
- Temperature Sensors (NTC Thermistors)
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