C2 on a Viessmann Vitotronic 200: Power supply: Compressor stops

What it means

The manual says: Power supply: Compressor stops.

Part involved: Power supply.

When it shows: Compressor stops.

Likely causes:

• Compressor power supply fault or phase monitor faulty.

Is it safe?

The heat pump stops until the fault clears or is reset.

Resetting itself: Not stated per code; Vitotronic messages remain until the cause is removed and are acknowledged with OK (6150133 p.82). Unremedied acknowledged faults are redisplayed the following day.

Manual reset: Acknowledge with OK on the programming unit (user level permitted per 5817913 p.56-57) after the cause is remedied.

What you can check

• Note the 2-character message code and message text shown on the Vitotronic 200 display (press OK for details) and give them to your heating contractor (operating instructions 5817913 p.56).
• You may acknowledge the message once with OK as described in the Vitotronic 200 operating instructions; if it reappears, do not keep acknowledging it - call your contractor.
• Check the heat pump breaker/isolator in the consumer unit is ON (do not repeatedly reset a breaker or RCD that keeps tripping).

What the engineer will check

• Check connections, power supply and phase connection. Check phase monitor. The switching signal of the phase monitor can be checked at terminal 215.2: See "Main ….

Who to ask for: Viessmann-trained heat pump engineer / qualified electrician.

Certification: Qualified electrician for work on electrical equipment (Viessmann safety instructions).

What you might notice

• No heating
• No hot water
• Keeps stopping / cutting out

Sources

• Service instructions Vitotronic 200 type WO1C heat pump control unit (air/water split & monobloc, brine/water) (6150133, 2023-07) ↗ · 6150133 VSA00004 · page 103 · Reviewed 23 September 2026

A code explains what the controller detected, not a confirmed root cause.

Reviewed: 23 September 2026