E20 High
Your boiler's temperature sensor has failed or is disconnected, meaning the system cannot accurately measure how hot the water is for your heating.
Technical description: Central heating thermistor sensor error
Typical repair cost: £90-160 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Protect yourself from future repair bills
A boiler cover plan would cover faults like E20 — no call-out fees, no surprises.
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Parts commonly replaced
- Central heating NTC thermistor
- Wiring harness
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