Your boiler is currently preparing itself to provide hot water quickly and is not actually reporting a fault.
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 and fan running (warm start)
What causes this fault?
This code appears when the boiler activates its pre-heat function to ensure hot water is delivered to your taps as quickly as possible. It is a standard operational sequence where the pump and fan run briefly to warm up the internal heat exchanger. Your boiler hasn't stopped working; it is simply preparing itself for use.
DIY fix possible
Check if the comfort mode or pre-heat setting is turned onWait a few minutes to see if the status changes to a normal heating codeMonitor for any actual fault codes starting with F if the boiler fails to fire
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.21 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Vaillant Ecomax 613 2 E 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.