Outdoor unit shuts down; E5 error; may be intermittent

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

Short circuit in compressor or wiring, Faulty inverter IPM, Poor electrical connections at power terminals, Power supply instability

Safety: High-voltage DC is present in inverter systems. Only trained personnel should access the power section.

Check terminal tightness: With power off, tighten all power and ground connections in the outdoor unit.
Inspect wiring: Look for signs of overheating or insulation damage on compressor and fan wires.
Power quality: Verify supply voltage is within Viessmann limits and not fluctuating excessively.
Technician repair: If E5 continues, the inverter module or compressor may need replacement after proper testing.

Professional Required 5/5

Inverter Power Module (IPM)

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