0B
FAULT CODE
Viessmann
Fan Speed Error — Wind Conditions
Medium Severity
Engineer Required
On Vitodens 200 boilers, code 0B indicates the fan has not idled correctly after an auto-reset, possibly due to severe wind conditions in the flue system. On Vitodens 100-W, indicates insufficient water flow.
Cold Weather Note
0B can occur in very windy conditions when the flue terminal is exposed to strong wind. May self-resolve when wind drops.
Step-by-Step Fix Guide
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Step 1
Check whether there are strong wind conditions affecting the flue terminal
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Step 2
Reset the boiler once
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Step 3 Engineer only
If fault persists, call a Gas Safe engineer to check the flue terminal and fan
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.