BoilerFaultCodesYour boiler has detected that the temperature readings coming from its internal sensors don't match up, so it has shut down to prevent overheating.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flow and return sensor anomaly detected.(incorrect temperature value shown on sensor.)
What causes this fault?
This fault occurs when the boiler's control board receives conflicting information from the two probes that monitor water temperature. It happens because one of the sensors has likely degraded and is sending an inaccurate electrical signal, making the boiler think the internal heat levels are unsafe. The system shuts down as a precaution because it can no longer accurately track how much heat is being transferred into your radiators.
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 0A15 — 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.