50048 on a Stiebel Eltron WPM heat pump manager / WPMsystem: Repeated instances of message number X-0048 has led to heat pump interlock
Short answer
On a Stiebel Eltron heat pump, 50048 means: Repeated instances of message number X-0048 has led to heat pump interlock. 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: Repeated instances of message number X-0048 has led to heat pump interlock.
Part involved: water flow / pump / booster heater.
When it shows: Repeated instances of message number X-0048 has led to heat pump interlock.
Likely causes:
- Remove the cause. 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
- Do NOT bleed radiators (Stiebel R290 manual: possible refrigerant ingress into heating water); contact your installer/service department.
- 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.
- Check the outdoor unit air intake/discharge is not blocked by leaves, snow or ice (air source units).
What the engineer will check
- Remove the cause. Then perform a reset of the heat pump via the WPM.
Who to ask for: Heating / heat pump engineer.
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