90
FAULT CODE
Viessmann
Coding Plug Fault
High Severity
Engineer Required
The boiler's coding plug cannot be read.
Step-by-Step Fix Guide
-
Step 1 Engineer only
A Gas Safe engineer should check the coding plug
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.