Mitsubishi mini split error codes explained (and possible fixes)

If your Mitsubishi mini split system is experiencing an issue, you may notice an error code flash on the display.

Here is a list of common Mitsubishi mini split error codes to help you fix the trouble and get it working again.

Mitsubishi mini split error codes – common error codes and possible solutions

This Mitsubishi mini split error codes list covers all fault codes across Mitsubishi mini split product range.

To make your life easier when attempting to repair your mini split, use the tips in this guide together with the information in your unit’s Service Handbook (go to the trouble-shooting section).

Mitsubishi mini split error code p1 –Mr Slim P series (A)

Return air thermistor fault(TH1) – check if TH1 is disconnected or there is an open/close circuit.

Mitsubishi mini split error code p1 – Mr Slim P series (K)

TH1 fault – check the return air thermistor(6.4K_ @20°C)

Mitsubishi mini split error code p6 – Mr Slim P series (A)

Freezing/Overheating of the indoor unit heat exchanger – This is mainly caused by reduced airflow through indoor coil. Other causes include Dirty filters/Fan motor problem/Blockages.

Mitsubishi mini split error code p6 – Mr Slim P series (k)

Frost protection in cooling (or Overheat protection in heating) has been detected by the indoor coil sensor – typical causes are lack of airflow or refrigerant charge issue.

Mitsubishi mini split error code p8 – Mr Slim P series (A)

Pipe temperature abnormal – this is primarily caused by refrigerant leakage. There is also a possibility the thermistor is mounted incorrectly.

Mitsubishi mini split error code p8 – Mr Slim P series (k)

Pipe/coil temperature abnormal – no temperature change registered at the indoor unit after nine minutes of operation. Probable reasons are tripped outdoor unit, refrigerant charge issue, or lack of airflow (at the indoor unit). Also check if TH2 is Faulty or not mounted correctly.

Mitsubishi mini split error code e6 – Mr Slim P series (A)

Indoor/outdoor communication problem– the Mitsubishi Mr Slim Error Code e6 commonly occurs if the outdoor unit is powered up before the indoor unit. If not, the drain pump (wired into S1 & S2) could be causing interference.

Mitsubishi mini split error code e9 – Mr Slim P series (A)

Communication failure [indoor to outdoor (S2/S3)] – for the Mitsubishi Mr Slim Error Code e9, check wired in pumps. Also check the indoor isolator. Finally, re-power in the correct sequence (indoor then outdoor).

Mitsubishi mini split error code u3 – Mr Slim P series (A)

Discharge thermistor fault- test and repair/replace.

Mitsubishi mini split error code u4 – Mr Slim P series (A)

Outdoor thermistor fault- test and repair/replace.

Mitsubishi mini split error code 1501 – Mitsubishi City Multi

High compressor shell temperature – check for gas shortage. There may also be insufficient indoor index running(comms room units).

Other Mitsubishi Mr Slim Error Codes (general)

Here now are other common Mitsubishi Mr Slim Fault Codes, their meaning, and troubleshooting tips:

Mitsubishi Mr Slim Error Code E0

Meaning: Signal transmitting/receiving fault (Indoor controller not responding to your remote controller signal.)

Likely Cause: During individual unit control, there is bad contact of the transmission wire Or the signal transmitting/receiving circuit may have malfunctioned.

Troubleshooting: Inspect the transmission wire/test with a different remote controller. If the error still remains, replace indoor controller board. In case a different error code appears, replace original remote controller.

Mitsubishi Mr Slim Error Code P1

Meaning: Issue with room temperature thermistor(RT1)

Likely Cause: Bad contact of the thermistor or damaged thermistor

Mitsubishi Mr Slim Error Code P2

Meaning: Fault with indoor coil thermistor(RT2)

Likely Cause: Bad contact of the thermistor or damaged thermistor

Troubleshooting Error Code P1 / Error Code P2

1. Check the thermistor.
2. Measure resistance of thermistor(The normal resistance should be 32°F····15kΩ 86°F·····4.3kΩ 50°F······9.6kΩ 104°F···3.0kΩ 68°F······6.3kΩ). If you found the resistance normal, replace indoor controller board.

Mitsubishi Mr Slim Error Code p3

Meaning: Signal transmission problem (Remote controller not responding to in-door controller signal.)

Likely Cause: Bad contact of the transmission wire/signal transmitting or receiving circuit faulty/Wrong operation (perhaps due to noise waves produced by other appliances).

Troubleshooting Error Code P3

• Check transmission wire.
• Test with a different remote controller- If “P3” still appears, replace indoor board. If another error code is displayed, replace original remote controller.
• Short-circuit between 1 & 2 of CN40 then attach CN40 to these units; 1: Second unit (in twin control) 2: Second & third units (in triple control) 3: Sub units (in group control).

Mitsubishi Mr Slim Error Code p4

Meaning: Drain sensor problem.

Likely Cause: 1: Bad contact of the transmission wire 2: Damaged thermistor

Troubleshooting Error Code P4

• Inspect the connector.
• Measure resistance of thermistor 1 – 3 (32°F ···6kΩ 59°F ···3.2kΩ 86°F ···1.8kΩ 41°F ···4.8kΩ 68°F ···2.6kΩ 95°F ···1.5kΩ 50°F ···3.9kΩ 77°F ···2.2kΩ 104°F 1.3kΩ ). If resistance is fine, replace indoor controller board.

Mitsubishi Mr Slim Error Code p5

Meaning: Drain pump malfunction.

Likely Cause: Issue with drain pump/damaged drain sensor

Troubleshooting: Start by checking the drain pump followed by the drain sensor (You want to check that the drop of water is on.)

How to troubleshooting Mitsubishi mini split P4/P5 Error Code (L) – video

Mitsubishi Mr Slim Error Code p6

Meaning: Freezing protection/overheating protection working.

Likely Cause: Short cycling of air cycle/Dirty air filter/Damaged fan /Abnormal refrigerant.

Troubleshooting: Clear obstructions(from the air cycle). Also, clean the airfilter. Next, Check the fan. Finally, check refrigerant temperature.

Mitsubishi Mr Slim Error Code p7

Meaning: System error

Likely Cause: Wrong address-setting Or Signal transmitting/receiving circuit (of remote controller) is faulty. Also check for wrong SW6-setting.

Troubleshooting: 1:Check the address-setting. 2:Test with a different remote controller (If other error code appears, replace original remote controller). 3: Check SW6 setting.

Mitsubishi Mr Slim Error Codes p8

Meaning: Outdoor unit issue

Likely Cause: 1:Incorrect wiring of the indoor/outdoor connecting wire 2: Reversed phase 3:Protection device working 4:Defective outdoor coil thermistor.

Troubleshooting: 1:Check indoor/outdoor connecting wire. 2:Check if the electric wiring is connected properly. 3:Check protection device. 4:Measure resistance of outdoor coil thermistor and replace outdoor controller board if the resistance is okay.

 

How do you reset a Mitsubishi mini split?

If you wish to reset your Mitsubishi mini split – this can help clear some error codes- simply power off and then back on.

 

Conclusion

If you’re still in trouble, contact a mitsubishi mini split error contractor near you. He/she will help you resolve all of your mitsubishi mini split error codes.

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Mitsubishi mini split troubleshooting guide for common problems