Mitsubishi M-Series wall units show errors as a count of blinks on the indoor unit's OPERATION INDICATOR lamp, such as 2 blinks for a sensor fault. P-Series units such as the PKA show check codes like P1, E6 or U4 on the wired remote, or as beeps after a wireless self-check. Mitsubishi's manuals say to stop using the unit and call your dealer.
Mitsubishi Electric M-Series wall units do not show letter codes. The OPERATION INDICATOR lamp on the indoor unit blinks a set number of times, and the blink count is the error. P-Series units such as the PKA wall unit show check codes like P1, E6 or U4 on the wired remote, or as beeps and blinks after a self-check from the wireless remote. Mitsubishi's owner manuals give one instruction for both: stop using the unit and call your dealer.
How to read the blinking lamp on an M-Series unit
The lamp does more than report faults, so check what it is doing first. In normal use, the MSZ-GL operating instructions say the lamp shows how close the room is to the set temperature, and a blinking lamp on a multi-zone system can mean standby mode.
A fault looks different. Mitsubishi's MSZ-GS indoor unit service manual (OBH874A) says the indoor fan turns off and the lamp blinks in a repeating pattern: a run of short blinks, then about 2.5 seconds dark. Count the blinks in one run, then count a second run to be sure. On most MSZ-GS models it is the upper lamp that blinks. On the larger GS30 and GS36 models it is the left lamp.
Mitsubishi M-Series blink codes
Codes from the troubleshooting check table in the MSZ-GS service manual, for the MSZ-GS06, 09, 12, 15, 18 and 24NA and the MSY-GS09 to 24NA. Mitsubishi says to make sure the symptom happens again before acting on it.
| Upper lamp | What it means | What you can check | Call a pro? |
|---|---|---|---|
| Blinks on and off every 0.5 seconds | Miswiring or serial signal error: the indoor unit gets no signal from the outdoor unit for 6 minutes, and neither unit runs | Stop using the unit | Yes |
| 2 blinks, then 2.5 seconds off | Indoor coil sensor or room temperature sensor is open or shorted | Stop using the unit | Yes |
| 3 blinks | Indoor fan motor: no speed feedback signal while the fan runs | Stop using the unit | Yes |
| 4 blinks | Indoor control system: the indoor board cannot read its memory | Stop using the unit | Yes |
| 5 blinks | Outdoor power system: the compressor stopped 3 times in a row on over-current or start-up failure within 1 minute of starting | Stop using the unit | Yes |
| 6 blinks | Outdoor temperature sensors open or shorted while the compressor runs | Stop using the unit | Yes |
| 7 blinks | Outdoor control system: an outdoor board cannot read its memory | Stop using the unit | Yes |
| 14 blinks or more | Another abnormality, including an indoor or outdoor temperature sensor fault | Do not restart until it is repaired | Yes |
| Lit, outdoor unit not running | Outdoor control system memory error | Stop using the unit | Yes |
The owner column is short because Mitsubishi's owner manuals are. The MSZ-FS operating instructions list a blinking operation indicator lamp among the times to stop using the air conditioner and consult your dealer, unless it is a multi-zone unit blinking on standby. For the 14-blink row, the service manual adds a warning not to start the unit again without a repair, to prevent hazards.
The failure mode recall function
If the lamp stopped blinking before you could count it, the unit may still remember the fault. The GS service manual describes a failure mode recall function that replays the stored fault on the lamp, set up with a button combination on the remote and its RESET button. The manual warns that the function must be released afterward or the unit cannot operate properly, so leave this one to your technician.
Get matched with a local HVAC technician
Networx matches you with vetted pros near you. Free, no obligation.
Mitsubishi P-Series check codes
P-Series units log check codes. The PKA-A12LA1 and PKA-A18LA1 service manual (TCH117, March 2023) lists them with the number of beeps and lamp blinks you get from a wireless remote self-check. The wired PAR-41MAA controller shows the code on its screen.
| Code (blinks) | What it means | What you can check | Call a pro? |
|---|---|---|---|
| P1 (1) | Intake (room air) sensor error | Power off, note the code | Yes |
| P2, P9 (2) | Pipe sensor error (TH2 or TH5) | Power off, note the code | Yes |
| E6, E7 (3) | Indoor and outdoor units are not communicating | Power off, note the code | Yes |
| P4 (4) | Drain sensor error, or float switch connector open | Power off, note the code | Yes |
| P5, PA (5) | Drain pump error, or compressor forced to stop by a water leak | Power off, note the code | Yes |
| P6 (6) | Freezing or overheating protection | Power off, note the code | Yes |
| EE (7) | Indoor and outdoor unit combination error | Power off, note the code | Yes |
| P8 (8) | Pipe temperature error | Power off, note the code | Yes |
| E4, E5 (9) | Remote controller signal receiving error | Power off, note the code | Yes |
| Pb (11) | Indoor fan motor error | Power off, note the code | Yes |
| Fb (12) | Indoor control system error, such as a memory error | Power off, note the code | Yes |
| PL (14) | Abnormal refrigerant circuit | Power off, note the code | Yes |
| E0, E3, E1, E2 (no beep) | Remote controller transmission error (E0, E3) or remote controller board error (E1, E2) | Power off, note the code | Yes |
Codes found by the outdoor unit start with a 3-second lamp-on before the blinks, so you can tell them from indoor codes:
| Code (blinks) | What it means | What you can check | Call a pro? |
|---|---|---|---|
| E9 (1) | Indoor and outdoor communication error, found by the outdoor unit | Power off, note the code | Yes |
| UP (2), UF (4) | Compressor over-current shutdown (UF: compressor locked) | Power off, note the code | Yes |
| U3, U4 (3) | Outdoor unit temperature sensor open or shorted | Power off, note the code | Yes |
| U2 (5) | High discharge temperature, or not enough refrigerant | Power off, note the code | Yes |
| U1, Ud (6) | High pressure, or overheating protection | Power off, note the code | Yes |
| U5 (7) | Heat sink temperature abnormal | Power off, note the code | Yes |
| U8 (8) | Outdoor fan protection stop | Power off, note the code | Yes |
| U6 (9) | Compressor over-current or power module abnormal | Power off, note the code | Yes |
| U7 (10) | Superheat abnormal from low discharge temperature | Power off, note the code | Yes |
| U9, UH (11) | Over-voltage or low voltage, or current sensor error | Power off, note the code | Yes |
On the PAR-41MAA, Mitsubishi prints Ud as UD and Fb as FB. If you also own another brand, do not carry the meanings across: Mitsubishi's U4 is an outdoor sensor fault, while Daikin uses U4 for a communication failure. Our Daikin error codes page has that list.
How to run the P-Series self-check
The PKA service manual gives the steps for the PAR-SL101A-E wireless remote:
- Press OFF/ON to stop the unit. If the weekly timer is on, turn it off.
- Hold MENU for 5 seconds. CHECK appears and the unit enters self-check mode.
- Use the arrow buttons to pick the refrigerant address of the indoor unit you want to check.
- Press SET. If there is an error, the indoor unit beeps and blinks the number that matches the code.
- Press OFF/ON to end the self-check.
Two beeps and nothing more means no error is on record. On the wired PAR-41MAA, the same history sits under Service, then Check, then Diagnosis, then Self check.
What Mitsubishi lets an owner check
Every Mitsubishi owner's manual we opened stops the owner at the code. The PKA operation manual says that when an error code appears, you should not try to repair the unit. Turn off the power switch at once and give your dealer the model name and what the remote shows. Before you get to that point, these checks come straight from the M-Series and P-Series manuals:
- Unit will not run: is the breaker on, and is an ON timer set?
- Just restarted: wait about 3 minutes. The unit protects itself.
- Heat stopped for a while: the outdoor unit may be defrosting, which takes up to about 10 minutes.
- Remote dead or weak: fit new AAA alkaline batteries, check the polarity and press RESET.
- Weak cooling or heating: clean the filters, and clear anything blocking the indoor or outdoor unit.
The MSZ-GL manual says to clean the filters every 2 weeks. The PKA manual explains filter cleaning but also says to ask authorized people to do it, so follow your own model's manual. For a safe power cycle, see our guide to resetting an air conditioner.
Also stop and call your dealer if water leaks from the indoor unit, the breaker trips often, you hear abnormal sounds or you find a refrigerant leak.
Blinking on a multi-zone system may not be a fault
On a multi-zone system, one outdoor unit cannot cool one room and heat another at the same time. The GS service manual says the indoor unit that started first sets the mode, and the others cannot run and blink their lamp. Set all the indoor units to the same mode. The PKA operation manual describes the same thing on the wired remote: the mode icon blinks when other indoor units on the outdoor unit already run in a different mode.
Indoor and outdoor units not communicating
This is the fault behind the 0.5-second blink on M-Series units and E6, E7 or E9 on P-Series units. The GS service manual's first checks are the power supply voltage and the wiring between the indoor and outdoor units, which are a job for a licensed HVAC technician. If your unit also cools or heats poorly between faults, our guide to a heat pump that is not cooling covers the other causes.
Which Mitsubishi models this page covers
All codes and steps come from Mitsubishi Electric Trane's own document library, opened in October 2026:
- M-Series: the MSZ-GS indoor unit service manual OBH874A (MSZ-GS06 to 36NA and NA2, MSY-GS09 to 36NA and NA2), and the operating instructions for the MSZ-GL06 to 15NA and MSZ-FS06 to 18NA.
- P-Series: the PKA-A12LA1 and PKA-A18LA1 service manual TCH117 and the PKA-A LA operation manual.
Other M-Series lines, such as the newer R-454B MSZ-GX and MSZ-FX wall units, may use different patterns. We could not open their service manuals, so check yours by model number or ask your installer. In every Mitsubishi manual we opened, the owner step for a fault was the same: stop and call your dealer.
Frequently asked questions
Why is the light blinking on my Mitsubishi mini split?
It depends on the pattern. On a multi-zone system, the lamp blinks on standby when another indoor unit is already running in a different mode, and the fix is to set every unit to the same mode. A repeating run of short blinks with about 2.5 seconds off is a fault. Count the blinks, stop using the unit and call your dealer.
How do I reset a Mitsubishi mini split error?
Mitsubishi's owner manuals do not give a reset for a fault. They say to stop using the unit, turn off the power and give your dealer the model name and the code or blink count. A technician can use the failure mode recall function to read a stored fault, but Mitsubishi warns that it must be released afterward or the unit will not run properly.
What does 2 blinks mean on a Mitsubishi mini split?
On MSZ-GS06 to 24 wall units, Mitsubishi's service manual says 2 blinks of the upper lamp, then 2.5 seconds off, means the indoor coil sensor or the room temperature sensor is open or shorted. Neither is an owner repair. Other M-Series models may use a different table, so check the service manual for your model number before you rely on it.
How do I check the error code on a Mitsubishi P-Series unit?
With the PAR-SL101A-E wireless remote, stop the unit, hold MENU for 5 seconds until CHECK appears, pick the indoor unit's refrigerant address with the arrows and press SET. The number of beeps and blinks gives the code. On the wired PAR-41MAA, go to Service, then Check, then Diagnosis, then Self check to see the code on the screen.
Is it safe to keep running a Mitsubishi with a blinking lamp?
Mitsubishi says no. Its owner manuals list a blinking operation lamp, water leaking from the indoor unit, a breaker that trips often, abnormal sounds and any refrigerant leak as times to stop using the air conditioner and consult your dealer. The only exception is a multi-zone unit blinking on standby, which is normal.
Founder of Home Caprice. Benas started the site to simplify HVAC after dealing with the heating and cooling in his first apartment.
