203 High
Your boiler is struggling to detect the temperature of your hot water cylinder, which usually means the system cannot heat your water correctly.
Technical description: Tank probe damaged
Typical repair cost: £110-190 (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 203 — no call-out fees, no surprises.
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Parts commonly replaced
- Hot water cylinder sensor (NTC probe)
- Sensor wiring harness
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