BoilerFaultCodesBaxi E12 Fault Code
The Baxi E12 fault code means: your boiler has detected that water isn't moving through the system correctly, which has caused it to shut down to prevent overheating.. It appears on 3 Baxi models in our database.
Technical description: Differential water flow switch fault (still open).
DIY fix possible
Check that all radiator valves are fully openEnsure your external heating pump is running if accessibleGently bleed your radiators to remove any trapped airReset the boiler using the reset button
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Baxi models that show the E12 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Baxi E12 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