BoilerFaultCodesYour boiler is overheating because the water isn't moving through the system fast enough to cool it down.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Difference between flow and return temperature too high: check pump and flow rate.
What causes this fault?
This fault occurs when the water inside the boiler gets too hot because it isn't moving away into your radiators quickly enough. The most common reasons are a failing pump that can't push the water, or a buildup of sludge and scale that has physically blocked the internal pipes. When the temperature difference between the water going out and coming back becomes too large, the boiler shuts down for safety.
This fault is frequently seen at the start of autumn when heating systems are switched back on after being idle all summer, which can cause internal pump components to seize.
DIY fix possible
Check that your radiator valves are openEnsure the system pressure is between 1 and 1.5 barRestart the boiler to see if the pump clears a temporary blockage
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 E20 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Remeha Quinta 30 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.