Viessmann Error Code ODU PH: Compressor pre-heat (Mini-Split)

Updated October 16, 2026 · by Aurora Star Tech Inc.

Viessmann error code ODU PH on a mini-split means: Compressor pre-heat. It is also called Viessmann diagnostic code ODU PH.

Low severityMini-SplitViessmann Vitocal 200-S DLCM(R/H)B multi-zone outdoor

Homeowner? What Viessmann code ODU PH means for you

Usually minor Your ductless mini-split is reporting: Compressor pre-heat. This code is usually informational or minor. The safe checks below often clear it; call us if it keeps showing up.

Safe things you can check yourself

Check the remote: fresh batteries and the right mode (Cool, Heat or Auto).
Check the breaker and the outdoor disconnect; both should be ON.
Open the front cover of the indoor unit and rinse the washable filters if they are dusty; let them dry before putting them back.
Keep the outdoor unit clear of snow, ice and leaves.
Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.

Call (647) 657-2977 Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Viessmann error code ODU PH mean?

Compressor crankcase pre-heating is on.

Applies to: DLCMRBH / DLCMHBH multi-zone outdoor units 18-48K (Midea, Carrier, Viessmann Vitocal 200-S)

Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

Viessmann models that use code ODU PH

DLCMHBH24CAK DLCMHBH30DAK DLCMHBH36DAK DLCMHBH48EAK DLCMRBH18BAK DLCMRBH36DAK DLCMRBH48EAK

Other Viessmann Mini-Split codes

Code	Meaning
ODU P1	High pressure protection (outdoor board)
ODU P2	Low pressure protection (outdoor board)
ODU P3	Current overload (outdoor board)
ODU P4	Discharge temperature protection (outdoor board)
ODU P5	Condenser high temperature (outdoor board)
ODU P6	Inverter module (IPM) fault (outdoor board)
ODU RO	Oil return cycle
Off	Timer off
On	Timer on
P0	Inverter module (IPM) fault
P1	Over or under voltage protection
P2	Compressor top overheat (OLP)

All Viessmann Mini-Split error codes →

Viessmann code ODU PH: homeowner questions

What does Viessmann code ODU PH mean?

Compressor pre-heat. Compressor crankcase pre-heating is on.

Is it safe to keep using my ductless mini-split with code ODU PH?

Usually yes. Code ODU PH is normally minor, but if it keeps coming back have it checked.

Can I reset Viessmann code ODU PH myself?

You can try one reset (power off for 30 seconds, then on). If Viessmann code ODU PH comes back, the cause is still there and a licensed technician should check it.

Who can fix Viessmann code ODU PH near me?

Aurora Star Tech Inc. repairs Viessmann ductless mini-splits in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: AC Running But Not Cooling: What to Check · Heat Pump Not Heating or Blowing Cold Air

Troubleshooting guides

Indoor unit leaking water All brands · Mini-Split
Poor capacity / high head All brands · Mini-Split
Water leaking All brands · Mini-Split
Discharge the inverter capacitors before service Viessmann · Mini-Split
Display shows a strange code or does not answer the remote - DLFSHB indoor Viessmann · Mini-Split
Multi-zone: one room heats, another will not cool - DLC multi-zone Viessmann · Mini-Split
Read live data with the outdoor check button (SW1) Viessmann · Mini-Split
Run the automatic wiring / piping correction Viessmann · Mini-Split

Source: DLCMRBH/DLCMHBH Multi-Zone Outdoor Service Manual (sold as Midea, Carrier and Viessmann Vitocal 200-S; Viessmann doc 6225551-03, 12/2024), Outdoor Unit Digital Display p.28; Automatic Wiring/Piping Correction p.6. Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.