BoilerFaultCodesYour boiler has detected an unusual temperature reading from the sensor that monitors water leaving the unit, causing it to shut down as a precaution.
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 out of range. (sensor measures a temperature not in normal range.)
What causes this fault?
This fault occurs when the boiler's internal computer receives a temperature reading that is physically impossible or outside of its safety limits. It is usually caused by a chemical failure inside the flow sensor itself or a loose connection in the wiring that interrupts the electrical signal. Because the boiler can no longer accurately monitor how hot the water is, it shuts down to prevent the system from 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 0A31 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
Affiliate links — we may earn a commission at no extra cost to you.