BoilerFaultCodesIdeal A short pulse every 4 seconds Fault Code
Also written as ASHORTPULSEEVERY4SECONDS — same fault.
The Ideal A short pulse every 4 seconds fault code means: your boiler is currently on standby and is running its built-in protection mode to prevent the internal pipes from freezing during cold weather.. It appears on 1 Ideal model in our database.
Technical description: Boiler in stand-by condition. Anti-freeze system active.
What causes the Ideal A short pulse every 4 seconds fault?
This occurs when the sensors inside your boiler detect that the internal water temperature has dropped to a level where there is a risk of freezing. To protect the heat exchanger and internal pipework from damage, the boiler automatically fires the burner to gently warm the system back up to a safe temperature. Once the water reaches a sufficient temperature, the pulse will stop and the boiler will return to normal operation.
This status is almost exclusively seen during the winter months or during period of extreme cold when the ambient temperature around the boiler drops significantly.
DIY fix possible
No action is required as this is normal operation.Ensure your gas and electricity supplies remain turned on so the protection can continue.Check that your external thermostat or programmer is calling for heat if you want the boiler to provide heating.
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Gas Safe Register →Ideal models that show the A short pulse every 4 seconds fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal A short pulse every 4 seconds 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