BoilerFaultCodesRemeha C1 Fault Code
The Remeha C1 fault code means: your boiler is busy clearing out any leftover gases before it tries to ignite again.. It appears on 2 Remeha models in our database.
Technical description: Boiler is ventilating
What causes the Remeha C1 fault?
This code appears when the boiler needs to clear the combustion chamber of old air and gases before it can safely start the ignition process. It is often triggered after a failed start attempt or a sudden interruption in the flame, causing the fan to run at high speed to vent the system. While it usually clears on its own, a persistent C1 code might suggest the fan is struggling to maintain the correct speed or the air pressure sensor is failing to detect the airflow.
DIY fix possible
Wait for up to 5 minutes as this is often a normal part of the boiler's operation sequence.Check if the display changes to a temperature or a different code after the ventilation cycle finishes.Perform a simple reset by pressing the 'R' or 'Reset' button if the code persists for a long period.
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Gas Safe Register →Remeha models that show the C1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Remeha C1 fault code information on this page is sourced and cross-checked against the official Remeha service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026