BoilerFaultCodesYour boiler has sensed that the water is heating up too quickly or unevenly, 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: Temperature differential exceeded
What causes this fault?
This fault occurs when the internal sensors detect that water isn't flowing away from the heat exchanger quickly enough, causing a rapid heat buildup. The most common reason is a failing circulation pump or a blockage in the system caused by a buildup of sludge and debris. It can also be triggered by air trapped within the boiler or a sensor that has become faulty and is giving incorrect readings.
This fault is more common in autumn when heating systems are turned back on after a long summer break, as pumps can seize and debris often settles while the system is inactive.
DIY fix possible
Check that your system water pressure is between 1 and 1.5 bar on the pressure gauge.Ensure all radiator valves and the boiler service valves are fully open.Gently bleed your radiators to remove any trapped air that might be blocking circulation.Press the reset button to see if the boiler restarts once it 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 E30 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Vokera Pinnacle 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.