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F01 FAULT CODE
Glow-worm

Return Temperature Sensor Fault (Betacom/Ultracom)

Medium Severity Engineer Required

On Glow-worm Betacom and Ultracom models, F01 (or F11) indicates a return heating temperature sensor fault.

Step-by-Step Fix Guide

  1. Step 1

    Turn off the boiler

  2. Step 2 Engineer only

    Call a Gas Safe engineer to test and replace the return NTC

Gas Safe Reminder

Work on gas appliances must be carried out by a Gas Safe registered engineer. The steps above cover safe checks a homeowner can perform - any internal component replacement requires a qualified professional. If in doubt, always call an engineer.

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