BoilerFaultCodesIdeal 43 Fault Code
The Ideal 43 fault code means: your boiler is struggling to control how much water flows through the system, which can prevent it from heating up correctly.. It appears on 2 Ideal models in our database.
Technical description: The flow limiter is not properly adjusted.
What causes the Ideal 43 fault?
This fault occurs when the boiler's internal sensors detect that water is moving through the system at an incorrect speed, usually triggered by an improperly set flow regulator. The most common reason is that the mechanical limiter has shifted out of its calibrated position or has become blocked by internal debris, preventing the boiler from managing heat transfer safely. It can also be caused by a sensor failing to accurately report the water speed to the main control board.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Ideal models that show the 43 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal 43 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 7 July 2026