BoilerFaultCodesYour boiler has detected that there is not enough water pressure or the pump isn't circulating water through the system properly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Fault on Pump or Low System Pressure
What causes this fault?
This fault occurs when the boiler's internal sensors detect that water isn't moving through the heat exchanger as it should, which can cause the unit to overheat. The most common reasons are that the water pressure has dropped too low for the system to operate, or the internal pump has seized or failed. Occasionally, a large air bubble trapped inside the pipework can also block the flow and trigger this error.
This issue is frequently seen in autumn when the heating is turned back on for the first time, as pumps can seize after being idle over the summer.
DIY fix possible
Check the pressure gauge on the front of the boiler; it should ideally be between 1 and 1.5 bar.If the pressure is too low, use the filling loop valves underneath the boiler to top it up slowly.Bleed any trapped air from your radiators and then re-check the pressure gauge.
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 27 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Potterton Performa 24 Eco 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.
Affiliate links — we may earn a commission at no extra cost to you.