BoilerFaultCodesYour boiler has shut down because the water inside it has become too hot.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flow temperature is higher than the set maximum temperature
What causes this fault?
This fault occurs when water cannot move through the boiler quickly enough to carry heat away, causing the internal temperature to reach a dangerous level. The most common reasons are a failed external pump that isn't pushing water to the radiators or a buildup of sludge and debris that has physically blocked the pipes or heat exchanger.
This issue often appears during the first cold spell of autumn when the heating is turned back on after sitting idle all summer, which can cause internal pump parts to seize.
DIY fix possible
Check that all radiator valves are fully open to allow water to circulate.Ensure the external pump (if visible) is running and not making a grinding noise.Press the Reset button once the boiler has had 15 minutes to cool 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 é1 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Remeha Avanta 18V 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.