Daikin VRV IV RXTQ-TA / RXTQ-TB error code L1
Inverter board abnormality
Which models this applies to. Outdoor unit
Quick answer
On Daikin VRV IV RXTQ-TA / RXTQ-TB, L1 is a fault. It means inverter board abnormality. A first thing to check: A failed inverter PCB.
- 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
- Read the other outdoor codes alongside L1, since the inverter board often reports a real condition on another part.
What L1 means on this model
The board that drives the compressor and outdoor fan with variable speed has reported a fault and the outdoor unit has stopped. It is the most expensive single board on the outdoor unit and the most common age related failure. Check the sensors feeding it before replacing it.
Symptoms you will notice
- Outdoor unit shows L1 and the system stops
- The system will not start
- The compressor and outdoor fan do not run
- The system has a history of high pressure or discharge temperature trips
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 inverter PCB
- A failed output stage on the board
- A wiring or connector fault at the inverter board
- A failed refrigerant pressure or temperature sensor circuit on the same board
- A failed main PCB that the inverter is reporting back
- Age and heat damage to the board over many years
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.
- Read the other outdoor codes alongside L1, since the inverter board often reports a real condition on another part.
- Check the connectors into the inverter board before concluding the board has failed.
Do not do these
- ×Do not replace the inverter board before checking the pressure and temperature sensors that feed it. A failed sensor circuit on the board presents the same way.
- ×Do not replace the compressor and the inverter board together as a set without proving which has failed, since that is an expensive way to fix one fault.
- ×Do not work inside the outdoor unit 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
Inverter PCB $500 to $1,200.
Labor
Two to four hours to diagnose 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.