F.17
FAULT CODE
Vaillant
Outside Temperature Sensor Short Circuit
Low Severity
Engineer Required
The outside temperature sensor (used for weather compensation) has short-circuited. Does not prevent heating but disables weather compensation.
Step-by-Step Fix Guide
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Step 1
Reset the boiler
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Step 2 Engineer only
If the fault persists, a Gas Safe engineer should inspect the outside sensor cable and connector
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.