Viessmann · Boiler

P.4 Top up heating water

Menu / mode display Vitodens 200-W B2HE

What the display is showing

Service message: system water needs topping up.

Applies to: Vitodens 200-W B2HE 85, 120, 150, 199

What to do

Fill and vent the system to the correct pressure.

Models that show this code

4 models in Vitodens 200-W B2HE

B2HE-120B2HE-150B2HE-199B2HE-85

Other codes on the same units

I.56 External demand active
I.57 External blocking active
I.59 Parameters restored
P.1 Service interval reached
P.8 Service due after burner hours
S.154 Internal flow switch open
S.60 Summer mode active
S.74 Heating suppression

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Source: Viessmann Vitodens 200-W B2HE 85/120/150/199 Service Instructions 6167 813-24 (09/2026), Further messages, p.74. Summarized in our own words; check the original manual for your model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.