Mini-Split Error Codes: How to Read Them and What to Do
Last updated Reviewed by Waseem Shahzad, Lead Technician
Smell gas or hear a carbon monoxide alarm? Leave the house first, then call 911 or the gas utility from outside.
What does a mini-split error code mean?
A code or blinking light means the unit stopped itself because a sensor or control saw something out of range. The code points to a category of fault, such as communication between the indoor and outdoor units, a temperature sensor, drainage or a protection shutdown. It narrows the search; it does not name the failed part.
Codes differ by brand and even by model series, so the same code can mean different things on two units. Always confirm the code against the owner's or installation manual for your exact model number, which is on a label on the side of the indoor unit and on the outdoor unit.
How do the major brands show their codes?
Some brands show a letter-number code on the indoor unit or remote; others blink the operation and timer lights in a pattern you count. Communication faults between the indoor and outdoor units are one of the most common codes on every brand, and the brand's own documentation names them.
- Mitsubishi Electric: many residential models report faults through the remote's check function or a blinking operation lamp; on many models, E6 is listed as an indoor-outdoor communication error.
- Fujitsu: the operation and timer lamps blink in counted patterns. Fujitsu notes that lamps blinking alternately can simply mean power was interrupted, and some service manuals list one operation flash with one timer flash as a serial communication error.
- Daikin: codes appear on the remote; on many ductless models, U4 is the indoor-outdoor communication fault.
- Samsung: codes such as E101 appear on the display, which Samsung service documentation lists as an indoor-outdoor communication error.
- LG: codes show as CH followed by a number; LG's support pages describe CH05 as a communication problem between the indoor and outdoor units.
These are examples only. Check the manual for your model before acting on any code.
What can you safely check yourself?
Write down the code or count the blinks, then check the filters, the power and the outdoor unit. A power reset clears some temporary faults. If the same code comes back, stop resetting and call; the unit is protecting itself from a real problem.
- Record the code: Write down the code or count the blinks of each light, and note what the unit was doing when it stopped.
- Clean the filters: Lift the front panel and rinse the mesh filters if they are dusty. Let them dry before refitting.
- Check the outdoor unit: Make sure it has power, is not buried in snow or leaves, and the fan is not blocked.
- Reset the power once: Turn the unit off at the breaker or disconnect for about five minutes, then back on. Some manufacturers recommend switching the indoor and outdoor breakers back on together.
- Watch for the code: If the same code returns, leave the unit off and call with the code and model number.
What should you not do?
Do not open the indoor or outdoor unit covers, touch the wiring or terminal block, or add refrigerant. Do not keep power-cycling a unit that keeps throwing the same code. Inverter boards hold charge after power is off, and the wiring between units carries line voltage.
If water is dripping from the indoor unit, turn it off to protect the wall and floor; that is usually a drain problem, like the one in our Commack mini-split leak repair.
What does K2 do when a mini-split shows a code?
We look up the code for your exact model, then test the parts it points to: communication wiring, sensors, drain, refrigerant pressures and the boards. Many codes come from dirty filters and coils, which we clean. Flare leaks are fixed by remaking the connection and pressure testing, not by topping up refrigerant.
A Babylon mini-split with a flashing light was back after a filter and coil cleaning; a Dix Hills basement unit got a coil clean and a refrigerant check. For how these systems work, read how a mini-split works.
Common questions
Is a blinking light on a mini-split always a fault?
Not always. Some brands blink lights for a power interruption, a test run or defrost. Count the pattern and check the manual for your model.
Will a power reset fix a mini-split error?
It can clear a temporary fault. If the same code comes back, the cause is still there, and repeated resets will not fix it.
Where do I find my mini-split model number?
On a label on the side or bottom of the indoor unit and on the outdoor unit. Have both when you call.
Need a technician?
Call or text us 24/7 from anywhere within 15 miles of Deer Park. You get a time window and the price before any repair.
Call 24/7: (631) 414-7141