Daikin VRV IV RXTQ-TA / RXTQ-TB error code JA
High pressure sensor abnormality
Which models this applies to. Outdoor unit
Quick answer
On Daikin VRV IV RXTQ-TA / RXTQ-TB, JA is a fault. It means high pressure sensor abnormality. A first thing to check: A failed high pressure sensor.
- Applies to
- Daikin VRV IV RXTQ-TA / RXTQ-TB
- Daikin VRV IV RXTQ heat pump codes · Heat Pump
- Type of code
- Fault
- Urgency: Needs attention soon
- First safe check
- Compare the reported pressure against an independent gauge reading, because a failed sensor and a real pressure problem present identically on the controller.
What JA means on this model
The high pressure sensor has reported a fault or is reading implausibly. Because this is the sensor behind the high pressure protection, a failure can stop the system from starting at all, and it is a frequent cause of technicians chasing a charge problem that does not exist. Verify against a real gauge first.
Symptoms you will notice
- Outdoor unit shows JA and the system stops
- The system will not start even in mild conditions
- The system reports high pressure related symptoms with no real high pressure
- The fault appeared after work on the outdoor unit
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 high pressure sensor
- A loose or corroded connector at the sensor
- A failed input on the outdoor main PCB
- A damaged or disconnected capillary line or pressure port
- A wiring fault in the sensor circuit
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 reported pressure against an independent gauge reading, because a failed sensor and a real pressure problem present identically on the controller.
- Check the connector at the sensor for a loose or corroded pin.
Do not do these
- ×Do not change the refrigerant charge in response to a pressure sensor code until the sensor has been verified against a real gauge. This code is a frequent cause of unnecessary charging.
- ×Do not work on the sensor connector with the power switch on.
When to call a technician
Book a technician, do not keep resetting it
This fault will not clear on its own. Every power cycle gives the control one more failed attempt, and repeated attempts are what turn a cheap part replacement into a seized or contaminated system.
- 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.
What it costs to fix
Parts
High pressure sensor $60 to $180.
Labor
One to two hours to test and replace.
DIY or technician
A technician job.
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.