Heat pumps · Error codes · Stiebel Eltron
20246Stiebel Eltron · WPM heat pump manager / WPMsystem (controller platform)
20246 on a Stiebel Eltron WPM heat pump manager / WPMsystem: Update failed
Short answer
On a Stiebel Eltron heat pump, 20246 means: Update failed. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Update failed.
Part involved: WPM/IWS firmware.
When it shows: Update failed.
Likely causes:
- Power supply briefly interrupted. MicroSD card removed in the update process. Bus connection between WPM and FET faulty. FET removed from the bus during the update process.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: unknown.
Manual reset: unknown.
What you can check
- Read and note the full message code and time from the WPM display (DIAGNOSIS / NOTIFICATIONLIST if accessible without a code).
- Check the heat pump and controller circuit breakers/isolators at the consumer unit are on.
What the engineer will check
- Power supply briefly interrupted. MicroSD card removed in the update process. Bus connection between WPM and FET faulty. FET removed from the bus during the update process.
Who to ask for: Heat pump service engineer (electrical/controls).
Certification: Qualified electrician competence for live-work on appliance electrics.
What you might notice
Sources
- WPM notification list (WPM V2.9) - multilingual; English section pp.15-26 (DOC-00081866) ↗ · WPM V2.9 · page 19 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026