F.52
FAULT CODE
Vaillant
Mass Flow Sensor Connection Fault
High Severity
Engineer Required
The mass flow sensor is not connected or is disconnected. The plug may not be connected or is incorrectly fitted.
Step-by-Step Fix Guide
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Step 1
Do not open the boiler casing
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Step 2
A Gas Safe engineer will need to check the mass flow sensor connection
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Step 3 Engineer only
The sensor plug or wiring harness may need refitting or replacing
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.