Frozen Condensate Pipe
Viessmann's specific code for a frozen or blocked condensate pipe. The most common Vitodens winter fault.
F4 EE is Viessmann's dedicated frozen condensate code. Almost always fixable at home by thawing the external pipe.
Step-by-Step Fix Guide
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Step 1
Locate the white plastic condensate pipe on the outside wall
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Step 2
Pour warm water (NOT boiling) along the full length of the exposed section
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Step 3
Wait until you hear gurgling sounds indicating the blockage has cleared
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Step 4
Reset the boiler — it should restart normally
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Step 5
If fault persists, call a Gas Safe engineer to check the internal condensate system
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.