BoilerFaultCodesMain E193 Fault Code
The Main E193 fault code means: your boiler has detected trapped air inside the system, which is preventing water from circulating properly to heat your home.. It appears on 1 Main model in our database.
Technical description: System air lock
DIY fix possible
Turn off and isolate the boiler from the power supply.Locate the bleed valves on your radiators, starting from the downstairs units and moving upstairs.Open the valves slightly with a radiator key to release trapped air until water flows steadily, then close them tightly.Check your boiler's pressure gauge and top up the system to 1.5 bar if necessary using the filling loop.Restart the boiler.
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Gas Safe Register →Main models that show the E193 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Main E193 fault code information on this page is sourced and cross-checked against the official Main service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026