407
FAULT CODE
Navien
Room Controller Communication Error
Low Severity
DIY Check Possible
The boiler has lost communication with the room controller or thermostat.
Step-by-Step Fix Guide
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Step 1
Check the thermostat batteries and replace if needed
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Step 2
Verify the controller is within range
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Step 3
Reset the boiler and controller
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.