E1
FAULT CODE
Viessmann
Outdoor Temperature Sensor Fault
Low Severity
Engineer Required
The outdoor temperature sensor is not reading correctly. Weather-compensated heating control will not function.
Step-by-Step Fix Guide
-
Step 1
Check the outdoor sensor cable for visible damage
-
Step 2
The boiler will still heat but without weather compensation
-
Step 3 Engineer only
A Gas Safe engineer can test and replace the 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.