E20 High
Your boiler is struggling to monitor its temperature correctly because a internal sensor is sending a faulty signal, preventing the heating from working properly.
Technical description: Central heating thermistor sensor fault
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
- NTC Central Heating Thermistor
- Wiring Harness
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