7B on a Viessmann Vitotronic 200: Room temp. sensor SKK: No cooling mode

What it means

The manual says: Room temp. sensor SKK: No cooling mode.

Part involved: Room temp. sensor SKK.

When it shows: No cooling mode.

Likely causes:

• Lead break, room temperature sensor, cooling circuit.

Is it safe?

The heat pump keeps running with some functions stopped.

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).
• Check the room thermostat/remote control and time-program settings are as expected.

What the engineer will check

• Check resistance value (NTC 10 k Ω) at plug F16 (see "Controller and sensor PCB") or on remote control unit.

Who to ask for: Viessmann-trained heat pump installer/service engineer.

What you might notice

• Controller / thermostat problem

Sources

• Service instructions Vitotronic 200 type WO1C heat pump control unit (air/water split & monobloc, brine/water) (6150133, 2023-07) ↗ · 6150133 VSA00004 · page 96 · Reviewed 23 September 2026

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

Reviewed: 23 September 2026