Common Daikin VRV fault codes for commercial systems (VRV III / VRV IV), what they mean, and whether it's safe to reset or needs a professional. Exact code sets can vary by model series — always confirm against your installation manual or ask us to check.
Reviewed by Lim Eng Yew (Ryder Lim), Founder & Managing Director, RY Lim Electrical & Aircond Engineering · Last reviewed: September 2026
| Code | Meaning | Common Cause | Action |
|---|---|---|---|
| Communication & System Codes (U-Series) | |||
| U0 | Shortage of refrigerant | Undercharge, faulty EEV, or sensor fault | Call Technician |
| U1 | Reversed or missing phase | Incorrect power phase wiring at the outdoor unit | Check First |
| U2 | Power supply fault | Voltage drop, faulty capacitor, or wiring fault | Check First |
| U3 | Check operation not executed | System commissioning/check run was not completed after installation or PCB replacement | Informational |
| U4 | Communication failure (indoor ↔ outdoor) | The most common Daikin VRV fault — usually a wiring or connector issue on the communication bus between units | Check First |
| Indoor Unit Codes (A-Series) | |||
| A1 | Indoor unit PCB defect | Faulty indoor control board | Check First |
| A3 | Drain level control malfunction | Blocked drain, faulty float switch or drain pump | Informational |
| A6 | Fan motor lock or overload | Obstructed fan, worn bearing, or motor fault | Check First |
| A9 | Electronic expansion valve (EEV) malfunction | Faulty EEV coil or blocked valve | Check First |
| Outdoor Unit & Compressor Codes (E-Series) | |||
| E1 | Outdoor unit PCB defect | Faulty outdoor control board | Check First |
| E3 | High pressure switch (HPS) activated | Dirty condenser coil, blocked airflow, or overcharge | Call Technician |
| E4 | Low pressure switch (LPS) activated | Refrigerant undercharge or blocked piping | Call Technician |
| E5 | Compressor overheat or lock (inverter) | Refrigerant shortage, blocked piping, or inverter fault | Call Technician |
| E6 | Compressor overcurrent / locked rotor (standard compressor) | Electrical or mechanical compressor fault | Call Technician |
| E7 | Outdoor fan motor malfunction | Fan fails to run, stalls, or reports abnormal signal | Check First |
| Refrigerant Circuit & Inverter Codes (F, H, L-Series) | |||
| F3 | Discharge pipe temperature too high | Low refrigerant, blocked condenser, or high ambient temperature | Call Technician |
| H3 | High pressure switch (HPS) itself faulty | Wiring break, connector failure, or switch defect | Check First |
| H9 | Outdoor air thermistor malfunction | Faulty sensor reading ambient temperature | Informational |
| L4 | Inverter heatsink overheating | Inverter cooling fin temperature too high — often airflow or fan related | Call Technician |
| L5 | Compressor / inverter fault (general) | Inverter module or compressor electrical fault | Call Technician |
U4 is a communication failure between the indoor and outdoor unit — the most common Daikin VRV fault. It's usually a wiring or connector issue on the communication bus rather than a major component failure, but it needs a technician to trace.
A single power cycle can clear a transient fault. But if the same code returns, stop resetting it — repeated cycling can mask the real fault or stress the compressor. Codes involving pressure switches, the compressor, or the inverter should be diagnosed by a technician, not repeatedly reset.
Yes. VRV III and VRV IV systems can assign slightly different meanings to the same code, and the exact fault detail is confirmed via the outdoor unit's diagnostic display or a service tool. This list covers the most common codes seen in the field; treat it as a starting point.
Send us a photo of the code and we'll help you understand it before booking a visit.