F11 High
Your boiler's internal sensor that monitors the temperature of the water returning to the unit has stopped communicating correctly, causing the system to shutdown for safety.
Technical description: Return sensor error – t-sensor damaged, short circuited, sensor damaged or wiring broken
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 F11 — no call-out fees, no surprises.
*Affiliate links — we may earn a commission at no extra cost to you. Prices shown are starting prices.
Parts commonly replaced
- Return NTC Temperature Sensor
- Wiring harness
- Electronic Control Board (PCB)
*Affiliate links — we may earn a commission at no extra cost to you.