BoilerFaultCodesYour boiler has sensed that the water returning from your radiators is dangerously hot, causing it to shut down 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: Return sensor above 95 °C
What causes this fault?
This fault occurs when water cannot move through your heating system quickly enough to carry heat away from the boiler, causing the temperature to spike. The most common reasons are a failed internal pump that has stopped spinning or a physical blockage in the pipework that is restricting the flow of water.
This fault is frequently seen at the start of autumn when heating systems are turned back on after months of inactivity, which can cause the pump to seize.
DIY fix possible
Check that all radiator valves are fully openEnsure there are no obstructions to the air ventsReset the boiler using the control knob once the system has cooled down
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 b19 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Vokera Hydra 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.