BoilerFaultCodesYour boiler has shut down because it has detected an internal temperature that is too high, often caused by a blockage or a pump failure.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety thermostat (STB) exceeded
What causes this fault?
This fault occurs when the water inside the boiler gets too hot, causing the safety sensor to trip and shut the system down to prevent damage. The most common reasons are a broken circulation pump that isn't moving the water away from the burner quickly enough, or a build-up of sludge and debris creating a blockage in the heat exchanger.
This issue often comes to light during the first cold snap of autumn when the heating is turned back on after being idle all summer, which can cause internal pump parts to seize.
DIY fix possible
Check that your radiator valves are open and not turned to zero.Verify that the boiler pressure is between 1 and 2 bar.Press the 'Reset' button on the control panel to see if the fault clears.
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E02 — no call-out fees, no surprises.
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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.
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