BoilerFaultCodesYour boiler has shut down because it has detected an unsafe build-up of heat or a lack of water circulation within the internal system.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety temperature limiter in central heating (CH) flow has tripped
What causes this fault?
This fault occurs when the water inside the heating unit becomes dangerously hot, triggering a safety sensor to shut everything down to prevent damage. The most common reasons are a pump failure that stops water from moving or a buildup of sludge and scale that blockages the internal pipework. It can also be caused by a simple lack of water pressure or a faulty sensor giving an incorrect reading.
This issue often surfaces during the first cold snap of autumn when a pump that has been idle all summer fails to restart or struggles to push through settled debris.
DIY fix possible
Check if your boiler pressure gauge is below 1 bar and top it up if necessaryEnsure all radiator valves and the main isolation valves under the boiler are fully openGently press the 'Reset' button on the boiler control panel after 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 E9 — no call-out fees, no surprises.
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Worcester Bosch CDi Classic 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.
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