Daikin Mini-Split Code U5
Warning
Signal transmission error between the indoor unit and the remote controller. Normal communication with the wired controller did not continue for the specified period.
Manual wording: “U5 Signal transmission error between indoor unit and remote controller”
Documented for: Systems with a wired wall remote controller
Likely causes, most common first
- Connection of two MAIN remote controllers when using two controllers
- Defective indoor unit PCB
- Defective remote controller
- Signal transmission error caused by noise
What you can safely check yourself
- Turn the system off at the breaker or disconnect switch, wait a minute, and turn it back on once
When to call a technician
If two wall controllers are installed, one must be set to SUB - that dip switch setting and the controller wiring are a technician's job.
A Daikin mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Service Manual - Multi-Split Type Air Conditioners RMXS-L Series (SiUS181631EA) (Daikin, RMXS48LVJU outdoor, BPMKS048A2U/049A3U branch provider, CTXG/CTXS/FTXS/CDXS/FDXS/FVXS/FFQ indoor units) · checked 2026-08-25