Heat pumps · Error codes · Sime
HdSime · SHP M Pro
Hd on a Sime SHP M Pro: Communication malfunction between master unit and slave unit
Short answer
On a Sime heat pump, Hd means: Communication malfunction between master unit and slave unit. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: Communication malfunction between master unit and slave unit.
Part involved: controller / PCB communication.
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.
What you can check
- Note the code shown on the controller and the model number on the unit's rating label before contacting your installer.
- Check that the heat pump's isolator and consumer-unit breaker are on; do not open any casing.
What the engineer will check
- Check communication cables and connectors between boards/controller.
- Check board power supplies.
- Check addressing and firmware compatibility.
- Replace the faulty board.
Who to ask for: Heat pump engineer.
Certification: Heat pump installer competence; F-gas and flammable-refrigerant (R32/R290) handling competence for any refrigerant-circuit work.
What you might notice
Sources
- Sime SHP M PRO Installation manual 6332386 R3 (IT/EN/ES/EL) ↗ · R3 · page printed p.57 (PDF p.128) · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026