Heat pumps · Error codes · Stiebel Eltron
34Stiebel Eltron · LWZ 304 SOL / LWZ 404 SOL (integral ventilation units)
34 on a Stiebel Eltron LWZ 304 SOL / LWZ 404 SOL: Flow sensor: Flow (rate) sensor fault
Short answer
On a Stiebel Eltron heat pump, 34 means: Flow sensor: Flow (rate) sensor fault. 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: Flow sensor: Flow (rate) sensor fault.
Part involved: temperature/pressure sensor.
When it shows: Flow (rate) sensor fault.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: unknown.
Manual reset: unknown.
What you can check
- Note the fault number shown on the programming unit display.
- Check the appliance breakers/MCBs at the consumer unit are on.
What the engineer will check
- Follow remedy in LWZ 304/404 SOL installation manual section 9.4; causes largely parallel LWZ 5-8 list.
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
- INSTALLATION LWZ 304 SOL / LWZ 404 SOL (English, via ManualsLib manual 1279865) ↗ · page 44 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026