Viessmann [F.102] fault codewhat it means and how to fix it

F.102 reads "No internet connection — Error with communication module — Check cables and plug-in connections between heat management unit and communication module." The 050-W B0HA/B0KA and B1GA tables spell the cause out as "Communication between heat management unit and WiFi communication module" with the same measure. The module is the part of the programming unit that talks to your router so the ViCare app can see the boiler, and when it cannot be reached the boiler carries on heating and simply notes that it is offline. It is a message, not a fault: nothing is locked out and there is nothing to reset. Two more codes belong here and appear only while a connection is being set up. Viessmann's operating instructions list "E10 — Connection to the home network cannot be established" with the note to check the connection to the router and whether the network password is correct, and "E12 — Connection to the server cannot be established", for which the advice is to re-establish the connection at a later time. On the 050-W the instructions add that the code is displayed in parts, first "E1" and then "0", which is worth knowing before reading it as an E1.

The householder steps are the ones Viessmann give for establishing the WiFi link: hold OK for about four seconds until the rotating bar appears and the WiFi symbol lights on the far left, then follow the ViCare app; the symbol flashes while connecting to the local network, glows dimly when the network is joined and brightly when the server is reached. Most F.102, E10 and E12 episodes are the router, the password or the internet connection rather than the boiler, and resolve themselves when the broadband comes back. A boiler that shows F.102 with a healthy network and a module that will not light its symbol at all has a cable or module problem inside the programming unit, which is the contractor's.

1. 1

   Check your router is on and other devices can reach the internet. If the boiler was mid-setup, E10 means the home network could not be joined — check the network password and that you are using a 2.4 GHz network — and E12 means the server could not be reached; Viessmann say to try again later.

2. 2

   To re-establish the link, hold OK for about four seconds until the rotating bar appears and the WiFi symbol lights at the far left of the display, then follow the ViCare app. The symbol flashes while connecting, glows dimly once on your network and brightly once the server is reached. If it never lights, call your heating contractor.