Daikin VRV IV RXTQ-TA / RXTQ-TB error code M1
Centralized controller board defect
Which models this applies to. System
Quick answer
On Daikin VRV IV RXTQ-TA / RXTQ-TB, M1 is a fault. It means centralized controller board defect. A first thing to check: A failed centralized controller board.
- 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
- Check whether the zone still heats and cools through its own controller, which distinguishes a controller board fault from a system fault.
What M1 means on this model
The board inside the centralized controller has reported a hardware fault. On a building management system this takes the zone offline for central control even though the heating and cooling itself is usually still running, so check the zone before chasing the refrigerant system.
Symptoms you will notice
- System shows M1 and the centralized controller stops responding
- Heating and cooling continues but the zone is not centrally controlled
- The controller shows no units or no data
- The fault followed a power event at the controller
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 centralized controller board
- A power supply failure on the controller board, often from a power event
- A failed output on the controller board
- Moisture or contamination on the board
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.
- Check whether the zone still heats and cools through its own controller, which distinguishes a controller board fault from a system fault.
- Check the controller supply after a power event, since controller boards are commonly damaged by surges.
Do not do these
- ×Do not chase this through the refrigerant system. M1 is a controller board fault and the system is usually still running.
- ×Do not open the controller 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
Centralized controller $400 to $1,200, or the board alone on some models.
Labor
One to three hours to replace and re-address.
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.