Autofroststat mode Low

Worcester Bosch Autofroststat mode Fault Code

Also written as AUTOFROSTSTATMODE — same fault.

The Worcester Bosch Autofroststat mode fault code means: your boiler has detected very cold temperatures nearby and has turned itself on to heat up its internal components and prevent your pipes from freezing.. It appears on 2 Worcester Bosch models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Boiler is running in frost protection mode because it is in a very cold environment.

DIY fix possible

Ensure the room where the boiler is located is kept slightly warmerCheck that no external windows near the boiler are left open during freezing weatherOnce the internal temperature rises, the boiler will automatically return to normal operation

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Worcester Bosch models that show the Autofroststat mode fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Worcester Bosch Autofroststat mode fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026