70
FAULT CODE
Viessmann
Outdoor Sensor Open Circuit
Low Severity
Engineer Required
The outdoor NTC sensor circuit is broken.
Step-by-Step Fix Guide
-
Step 1 Engineer only
Check outdoor sensor cable
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.