BoilerFaultCodesYour boiler is undergoing a brief, normal startup process where the internal pump circulates water before the burner ignites.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: pump pre-run
What causes this fault?
This code appears when the boiler's internal computer tells the pump to start moving water through the system before the gas is ignited. It is a standard safety and efficiency check designed to ensure there is enough flow to carry heat away from the heat exchanger. This short delay is a normal part of the ignition sequence and does not mean anything has broken.
DIY fix possible
No action is required; this is a normal status code and not a fault.Wait approximately 20 to 60 seconds for the boiler to move to the next stage of operation.If the code persists for several minutes without the boiler firing, try resetting the unit.
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 S.02 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Glow-worm Ultrapower sxi 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.