BoilerFaultCodesBaxi 312 Fault Code
The Baxi 312 fault code means: your boiler is currently running a programmed safety cycle to remove air bubbles from the system, which is a normal process and will stop automatically in about 7 minutes.. It appears on 2 Baxi models in our database.
Technical description: De-aeration is taking place (approximately 7 minutes).
DIY fix possible
Wait 7 to 10 minutes for the automatic process to completeEnsure your radiator valves are open to help move the airMonitor the boiler display to see if it returns to normal operation once the timer finishes
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Baxi models that show the 312 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Baxi 312 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