BoilerFaultCodesYour boiler has likely overheated because the water isn't moving through the system properly or a safety sensor has detected a temperature that is too high.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: High limit protection – possible flow temperature sensor not active or incorrectly located, no system circulation
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature, triggering a safety shutdown. The most common reasons are a pump failure that prevents water from moving, or a buildup of debris and sludge that blocks the heat exchanger.
This issue is more frequent during the first cold spell of autumn, when pumps that have been idle all summer often seize up upon being restarted.
DIY fix possible
Check that your radiator valves and isolation valves are fully openEnsure your system pressure is topped up to between 1 and 1.5 barPress the Reset button on the control panel to see if the fault clears
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 A03 — no call-out fees, no surprises.
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Ferroli Modena HE 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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