BoilerFaultCodesYour boiler has shut down because the water returning from your radiators has become too hot, usually caused by a circulation problem.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Return sensor high temperature intervention
What causes this fault?
This fault occurs when the water coming back into the boiler from your heating system is much hotter than it should be, suggesting the heat isn't being distributed to your radiators. The most common reason is that the internal pump has failed or is struggling to push water through the pipes, causing heat to build up inside the unit. In some cases, a blockage in the system or a faulty temperature sensor can also trigger this safety shutdown.
This issue often surfaces during the first cold spell of autumn when the heating is turned on after being stagnant all summer, which can cause the pump to seize.
DIY fix possible
Check that at least two or three radiators have their valves turned fully openEnsure your central heating pump is running and hasn't seizedCheck the system pressure gauge and top up to 1.5 bar if it is low
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 49 — 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.