F5 High
Your boiler has lost its ability to monitor the temperature of the water returning from your radiators, often causing it to shut down to prevent damage.
Technical description: Return thermistor fault
Typical repair cost: £90-180 (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 F5 — no call-out fees, no surprises.
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Parts commonly replaced
- Return Thermistor (NTC Sensor)
- Wiring Harness
- Main PCB
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