E31 High
Your boiler has lost its digital connection with your external smart thermostat or heating controls, meaning it cannot receive instructions to turn on.
Technical description: OpenTherm communication error
Typical repair cost: £70-180 (including labour)
DIY fix possible
Check that your external thermostat or wall control is powered on and has fresh batteriesEnsure the wires connecting your thermostat to the boiler haven't been accidentally bumped or damagedTurn the boiler off at the main power switch, wait 30 seconds, and turn it back on to reset the connection
Protect yourself from future repair bills
A boiler cover plan would cover faults like E31 — no call-out fees, no surprises.
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Parts commonly replaced
- External Thermostat Unit
- OpenTherm Interface Module
- Control Wiring
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