Autofrostat Function Low

Worcester Bosch Autofrostat Function Fault Code

Also written as AUTOFROSTATFUNCTION — same fault.

The Worcester Bosch Autofrostat Function fault code means: your boiler has detected that the internal temperature is very low and has automatically activated its built-in frost protection mode to prevent the system from freezing.. It appears on 3 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: No demand and primary temperature below 8°C. Monitor central heating sensor: Below 5°C / 5°C to 9°C / Above 9°C

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Worcester Bosch models that show the Autofrostat Function fault code

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

Source

Worcester Bosch Autofrostat Function 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 7 July 2026