50026 on a Stiebel Eltron WPM heat pump manager / WPMsystem: Sensor value of "low pressure sensor" outside the permissible range
Short answer
On a Stiebel Eltron heat pump, 50026 means: Sensor value of "low pressure sensor" outside the permissible range. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Sensor value of "low pressure sensor" outside the permissible range.
Part involved: temperature/pressure sensor.
When it shows: Sensor value of "low pressure sensor" outside the permissible range.
Likely causes:
- Check sensor, leads and the relevant plug-in connectors, and replace if faulty. Then perform a reset of the heat pump via the WPM.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: no.
Manual reset: yes - reset of heat pump via WPM after cause removed (contractor).
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.
- Check the heating system pressure gauge reading is in the normal range stated by your installer.
What the engineer will check
- Check sensor, leads and the relevant plug-in connectors, and replace if faulty. Then perform a reset of the heat pump via the WPM.
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 26 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026