A.62 on a Viessmann One Base: Lead break, feedback signal, circulation pump heating circuit 1
Short answer
On a Viessmann heat pump, A.62 means: Lead break, feedback signal, circulation pump heating circuit 1. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Lead break, feedback signal, circulation pump heating circuit 1.
Part involved: Lead break, feedback signal, circulation pump heating circuit 1.
When it shows: System characteristics: No checks possible for secondary pump/heating circuit pump, heating/cooling circuit 1.
Likely causes:
- Lead break, PWM signal, secondary pump/heating circuit pump, heating/cooling circuit 1.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: Not stated per code in Viessmann document 6199893 GB 01/2026 (VSA00009).
Manual reset: User may acknowledge via HMI after noting the code (6249162 p.57); the message returns if the cause persists.
What you can check
- On the HMI, tap the message and "?" to read the system characteristics and Viessmann's user tips; note the code (e.g. F.xxx) and text for your contractor (operating instructions 6249162 p.57).
- Acknowledge the message once via the HMI; do not acknowledge fault messages several times in quick succession (6249162 p.58) - notify your contractor.
- Check the system pressure shown on the HMI "System overview" (6249162 p.35) or pressure gauge and report a low reading; make sure the filling loop is closed.
What the engineer will check
- Isolate the system from the power supply. Wait at least 2 min. Switch on the system.
- If the message appears often: Replace secondary pump/heating circuit pump, heating/cooling circuit 1.
Who to ask for: Viessmann-trained heat pump installer/service engineer.
What you might notice
Sources
- Service instructions for contractors: Heat pumps in monoblock design incl. hybrid – System configuration and diagnostics (Vitocal 150-A/151-A/250-A/252-A, IDU-A, AWMOF-151/251, AquaSnap 30AWH, BI-BLOC R290) (6199893 GB 01/2026) ↗ · 6199893 GB 01/2026 (VSA00009) · page 203 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026