Viessmann DC Bus Voltage Protection

System stops; P0 error; may occur under heavy load

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Supply voltage too high or too low, Faulty PFC (power factor correction) circuit, Loose power connections, Inverter board failure

Safety: High-voltage DC present; only qualified personnel should access the power electronics.

Measure supply voltage: Confirm that mains voltage is within the range specified by Viessmann.
Check connections: Tighten all line and neutral terminals and verify proper grounding.
Technician repair: If supply is normal, the inverter/PFC section on the outdoor PCB may be defective and require replacement.

Professional Required 5/5

Outdoor Inverter Control Board

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