Heat pumps · Error codes · Stiebel Eltron
20507Stiebel Eltron · WPM heat pump manager / WPMsystem (controller platform)
20507 on a Stiebel Eltron WPM heat pump manager / WPMsystem: ILS update failed
Short answer
On a Stiebel Eltron heat pump, 20507 means: ILS 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: ILS update failed.
Part involved: WPM/IWS firmware.
When it shows: ILS update failed.
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
- Consult Stiebel Eltron service for this message.
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 21 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026