E321 Medium
Your boiler has a faulty temperature sensor responsible for tracking the heat of your tap water, which usually results in inconsistent or no hot water.
Technical description: Hot water negative temperature coefficient (NTC) fault.
Typical repair cost: £100-£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 E321 — no call-out fees, no surprises.
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Parts commonly replaced
- DHW NTC thermistor
- NTC sensor wiring harness
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