BoilerFaultCodesIdeal 35 Fault Code
The Ideal 35 fault code means: your boiler's internal control module is failing to communicate with the fan, causing the system to shut down immediately after trying to start.. It appears on 1 Ideal model in our database.
Technical description: BIM is defective or not properly connected, when started, the fan will rotate for a moment and then stops.
What causes the Ideal 35 fault?
This fault occurs when the boiler's internal computer loses its connection with the fan, which is responsible for pushing exhaust gases safely out of the flue. Because the system cannot verify that the fan is spinning at the correct speed, it shuts down immediately to prevent an unsafe build-up of heat or gases. The most common cause is a failure in the electronic interface chip or a loose wire that has vibrated out of place over time.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Ideal models that show the 35 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal 35 fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026