BoilerFaultCodesYour boiler has detected that a key internal sensor responsible for tracking water temperature is either broken or disconnected, causing the system to stop working for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flow temperature sensor error (Flow temperature sensor not connected or defective)
What causes this fault?
This fault occurs when the boiler's control board loses communication with the sensor that monitors the temperature of the water leaving the unit. It is usually caused by the internal sensor failing due to age or a loose electrical connection between the sensor and the main wiring harness. For safety, the boiler stops firing because it can no longer accurately measure how hot the water is becoming.
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 36 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Remeha Selecta is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.