H23 on a Dimplex LA MI inverter outdoor air-to-water: Refrigerant liquid temperature sensor defective or disconnected
Short answer
On a Dimplex heat pump, H23 means: Refrigerant liquid temperature sensor defective or disconnected. 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: Refrigerant liquid temperature sensor defective or disconnected.
Part involved: Refrigerant liquid temperature sensor (CN-TH1 loom).
Likely causes:
- Sensor disconnected.
- Sensor defective.
- Main water PCB.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: Clear via control panel per Dimplex article (method shown as image).
What you can check
- Until an engineer attends, switch on the electric backup per the Dimplex guide 'How do I switch on the backup on the LA-MI heat pump?' (GDHV help centre).
- Note the code and contact the installer or Dimplex service.
What the engineer will check
- Isolate the heat pump from mains before any work.
- Check CN-TH1 on main water PCB.
- Check probe resistance.
Who to ask for: heat pump service engineer / heating engineer.
Certification: Electrical competence (Part P / qualified electrician) for work inside control panels.
What you might notice
Sources
- GDHV Help Centre article: i have h23 error on my la mi heat pump what does this mean ↗ · GDHV article (modified 2023-02) · page n/a (web article) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026