F.83
FAULT CODE
Vaillant
Flow/Return Temperature Sensor Error
High Severity
Engineer Required
Both the flow and return temperature sensors are reading incorrectly or giving impossible readings.
Step-by-Step Fix Guide
-
Step 1 Engineer only
Call a Gas Safe engineer to test both NTC sensors and their wiring
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.