F.01
FAULT CODE
Vaillant
Return Temperature Sensor Interruption
High Severity
Engineer Required
The return NTC temperature sensor has a faulty connection or open circuit. The return sensor monitors the temperature of water returning from the radiator system.
Step-by-Step Fix Guide
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Step 1
Check that the boiler has power
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Step 2
Do not attempt repairs yourself
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Step 3 Engineer only
A Gas Safe engineer needs to test the wiring and replace the return NTC 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.