Daikin VRV IV RXTQ-TA / RXTQ-TB error code CJ
Remote controller thermistor abnormality, warning
Which models this applies to. Indoor unit
Quick answer
On Daikin VRV IV RXTQ-TA / RXTQ-TB, CJ is a fault. It means remote controller thermistor abnormality, warning. A first thing to check: A failed thermistor inside the remote controller.
- Applies to
- Daikin VRV IV RXTQ-TA / RXTQ-TB
- Daikin VRV IV RXTQ heat pump codes · Heat Pump
- Type of code
- Fault
- Urgency: Worth keeping an eye on
- First safe check
- Compare the temperature shown on the controller against a separate thermometer in the same room, since a drifting controller thermistor produces a comfort complaint rather than a hard stop.
What CJ means on this model
The sensor in the room controller has reported a fault, so the unit has lost or distrusts the room temperature reading. Daikin treats this one differently from the other warnings and says the system may keep running depending on the conditions, which means it may be running on another temperature source in the system.
Symptoms you will notice
- Indoor unit shows CJ with the operation lamp lit
- The unit may or may not still heat and cool
- The room does not hold the temperature set on the controller
- The fault appears in a particular zone rather than the whole system
Common causes
The code tells you what the control detected, not which part failed. These are the causes we see most often, roughly in order of likelihood:
- A failed thermistor inside the remote controller
- A wiring fault in the controller cable
- A failed controller input on the indoor unit
What you can safely check
These are homeowner-level checks. None of them need you to open a live electrical compartment or work on gas.
- Compare the temperature shown on the controller against a separate thermometer in the same room, since a drifting controller thermistor produces a comfort complaint rather than a hard stop.
- Check the controller cable and connectors, particularly at the controller end where the cable is moved most.
Do not do these
- ×Do not calibrate the room by setting the controller a long way off the real temperature to compensate. That hides a failing sensor and costs comfort elsewhere.
- ×Do not open the controller with the power switch on.
When to call a technician
No call needed yet, but write it down
Note the date and the exact code, and watch whether it comes back. If it turns into a repeat fault or starts affecting performance, that is when it becomes worth a technician.
- The refrigerant circuit is sealed and legally requires licensed handling. Opening it without certification releases refrigerant and can put the whole system in violation of regulation, so a low-pressure or high-pressure fault on this equipment is a call-out, not a weekend job.
- If the appliance has stopped mid-cycle, is making a noise you have not heard before, or smells burnt, stop reading here and call. Those are symptoms of something the fault code does not describe well enough.
A technician job for the controller and its cable.
What it costs to fix
Parts
Remote controller $120 to $300. Controller cable $40 to $120.
Labor
One to two hours to diagnose and replace.
DIY or technician
A technician job for the controller and its cable.
Typical US part and labor ranges, 2026. They vary by region, model and contractor, so treat them as a planning figure, not a quote.
Scope of this code
- Code table
- Daikin VRV IV RXTQ heat pump codes
- Models in scope
- Daikin VRV IV RXTQ-TA / RXTQ-TB
- Checked
- Confirm on your own unit
- Find the model number on the data plate, then check this code in the service manual for that model. Manufacturers revise code tables between model years, and a revised board can renumber a fault.