BoilerFaultCodesYour boiler has stopped working because it cannot properly detect the temperature or movement of the water inside the system.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flow sensor disconnected – check the correct positioning and operation of the flow sensors
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. The most common reason is that the sensor has developed an internal electrical failure or the thin wires connecting it to the main computer have become loose or damaged. Because the boiler can no longer safely tell how hot the water is, it shuts down immediately to prevent overheating.
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 A41 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Ferroli Modena HE 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.