Fujitsu Mini-Split Code 41
Soft lockoutShown as: OPERATION lamp blinks 4 times, TIMER lamp blinks 1 time, ECONOMY lamp blinking continuously
Indoor room thermistor error. The room temperature sensor in the indoor unit has read an impossible temperature, meaning it is open or shorted.
Manual wording: “Indoor Room Thermistor Error - Room temperature thermistor detected an abnormal temperature.”
Documented for: RGLX, RL2/RLS2/RLS3/RLB/RLXB wall mounted, RLF/RLF1 multi-zone
Likely causes, most common first
- Open or shorted room temperature thermistor
- Thermistor resistance out of specification
- Failed indoor controller PCB
What you can safely check yourself
- Turn the power off at the breaker for about 5 minutes and back on to see whether the code clears
When to call a technician
The room thermistor is behind the indoor unit's front panel and has to be ohm-checked against Fujitsu's resistance table. Have a technician replace it.
A Fujitsu mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- 410A Mini-Split Troubleshooting Guide (Part # 6-26-FG2020 Rev. 5/2019) (Fujitsu General America, Inc., All R410A Halcyon mini-splits: RGLX, RL2/RLS3/RLS3H/RLS3Y/RLB/RLXB/RLXEH wall mounted, RLF/RLF1 multi-zone indoor units, RLXFZ multi-zone outdoor units, RML/RMLQ, RULX/RSLX universal-mount, RCLX cassettes) · checked 2026-08-25