F55
FAULT CODE
Glow-worm
CO Sensor Fault
High Severity
Engineer Required
The carbon monoxide safety sensor is not reading correctly.
Step-by-Step Fix Guide
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Step 1
Do not ignore this fault
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Step 2 Engineer only
A Gas Safe engineer must inspect the CO sensor and combustion quality
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.