BoilerFaultCodesYour boiler's fan is not running at the correct speed or has stopped working entirely, which means the system cannot safely clear exhaust fumes and has shut down as a precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: DC burner
What causes this fault?
This fault occurs when the boiler's internal safety checks detect that the fan isn't spinning fast enough to safely push exhaust fumes out of the flue. The most common reason is a mechanical failure within the fan motor or a buildup of debris that prevents it from turning freely.
This fault is slightly more frequent during windy winter periods, as strong gusts can sometimes create back-pressure in the flue that puts extra strain on a failing fan motor.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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 C6 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Worcester Bosch WR325 RSF 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.