BoilerFaultCodesYour boiler's fan is not spinning fast enough to safely clear away exhaust fumes, causing the system to shut down for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Fan speed too low.
What causes this fault?
This fault occurs when the boiler's control board detects that the internal fan is spinning slower than the required safety threshold. The most common reasons are a build-up of dirt within the fan mechanism, a blockage in the air supply tubes, or the motor itself failing after years of use. Because the fan cannot effectively push exhaust gases out of the flue, the boiler shuts down as a vital safety precaution.
This fault is slightly more common in winter as fans often work harder during cold spells, which can cause older, weakened fan motors to finally seize or fail.
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 C1 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Worcester Bosch RD 532i RD 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.