30
FAULT CODE
Viessmann
Boiler Water Temperature Sensor Short Circuit
Medium Severity
Engineer Required
The main boiler water temperature sensor (NTC) has short-circuited. On some Viessmann models the burner continues at an adjustable high limit; on others it is blocked.
Step-by-Step Fix Guide
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Step 1
Turn off the boiler
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Step 2 Engineer only
Call a Gas Safe engineer to test and replace the boiler water temperature sensor
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.