HVACopediaViessmann · Mini-split
ODU E3 IPM to main board communication error (outdoor board)
What the control is telling you
Outdoor board display. Indoor shows PC40.
Applies to: DLCMRBH / DLCMHBH multi-zone outdoor units 18-48K (Midea, Carrier, Viessmann Vitocal 200-S)
Test and repair steps
- Safety kill power at the disconnect and wait for the inverter capacitors to discharge before touching boards or wiring.
- With power on, check that at least one LED on the IPM board is lit.
- Check the signal cable between the IPM and main board. At the plug: black to white about 5 V DC, black to red about 12 V DC.
- Reseat the cable and retry.
- Still faulty replace the IPM board, then the outdoor main board, then the whole electric control box.
Models that show this code
7 models in Viessmann Vitocal 200-S DLCM(R/H)B multi-zone outdoor
Other codes on the same units
- ODU 00 Wiring / piping check finished
- ODU CE Automatic wiring / piping check running
- ODU E0 Outdoor EEPROM error (outdoor board)
- ODU E2 Indoor / outdoor communication error (outdoor board)
- ODU E4 Outdoor or T2B sensor fault (outdoor board)
- ODU E5 Over or under voltage (outdoor board)
- ODU E6 PFC module protection (outdoor board)
- ODU E8 Outdoor fan speed fault (outdoor board)
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Source: DLCMRBH/DLCMHBH Multi-Zone Outdoor Service Manual (sold as Midea, Carrier and Viessmann Vitocal 200-S; Viessmann doc 6225551-03, 12/2024), Table 27 Outdoor Unit Digital Codes p.32; diagnosis p.49-50. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
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.