BoilerFaultCodes E321 Medium Warning
Your boiler has detected an issue with the sensor that monitors the temperature of your hot water, meaning your taps may not get warm.
Book a service
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: Hot water fault
What causes this fault?
This fault occurs when the sensor responsible for measuring the temperature of your hot water fails or sends an incorrect signal. The most common reason is that the internal component has worn out over time or the electrical connection between the sensor and the main control board has become loose or damaged.
Typical repair cost £90-160 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →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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