Mitsubishi Mini-Split Error Code P1: How to Fix It

Medium 30-45 minutes Medium Severity Verified June 2026
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Error Code
P1
Brand
Mitsubishi
Product Type
mini_split
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-45 minutes
Error code P1 on a Mitsubishi mini-split indicates a short circuit in the indoor coil thermistor. This sensor monitors the temperature of the indoor coil, and a short can cause your system to stop working or run inefficiently. Follow this guide to diagnose and potentially replace the thermistor.
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Tools You'll Need

How to Fix Error Code P1

  1. Power Off the System

    Always disconnect power before servicing to avoid electric shock.

  2. Access the Indoor Coil Thermistor

  3. Test the Thermistor with a Multimeter

    Be careful not to damage connector pins.

  4. Replace the Faulty Thermistor

  5. Reassemble and Test

Parts You May Need

Indoor coil thermistor
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Indoor coil thermistor
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Indoor coil thermistor
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Indoor coil thermistor
Check Price on Amazon
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When to Call a Professional

If you're not comfortable working with electronics or the error persists after replacing the thermistor, contact a certified HVAC technician. The issue could be a faulty control board or wiring problem.

Frequently Asked Questions

What does error code P1 mean on a Mitsubishi mini-split?
Error code P1 indicates a short circuit in the indoor coil thermistor sensor. This sensor monitors the evaporator coil temperature. When shorted, the system may stop heating/cooling or show erratic behavior.
Can I run my mini-split with error P1?
It is not recommended. The system may operate without proper temperature sensing, leading to inefficiency, freeze-up, or compressor damage. Turn off the unit and repair it promptly.
How much does it cost to fix Mitsubishi error code P1?
If DIY, the thermistor part costs $10-$30. Hiring a pro may cost $150-$300 including service call and part. Prices vary by location.
Where is the indoor coil thermistor located?
It is attached to the indoor coil (evaporator) behind the front panel. Look for a small plastic sensor with two wires clipped onto the coil tubing or inserted into the fins.
Can a dirty filter cause error P1?
No, error P1 is a sensor-related fault. However, a dirty filter can cause other issues like poor airflow. Check and clean filters regularly.

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