BoilerFaultCodesBaxi E4 Fault Code
The Baxi E4 fault code means: your boiler is having trouble moving water around the system properly before it fires up, often caused by trapped air or low pressure.. It appears on 1 Baxi model in our database.
Technical description: Pre-circulation fault
DIY fix possible
Check the pressure gauge and top it up to 1.5 bar if it is too lowEnsure all radiator valves and isolation valves under the boiler are fully openGently bleed your radiators to remove any trapped air from the systemReset the boiler by turning the selector switch to 'R' for five seconds
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Baxi models that show the E4 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Baxi E4 fault code information on this page is sourced and cross-checked against the official Baxi service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026