Mitsubishi Mini Split Error Code PB: How to Fix It

Medium 30-60 minutes Medium Severity Verified June 2026
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Error Code
PB
Brand
Mitsubishi
Product Type
mini_split
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Error code PB on a Mitsubishi mini split indicates a short circuit in the outdoor coil thermistor (temperature sensor). This sensor monitors the outdoor coil temperature, and if it shorts, the system stops to prevent damage. The fix typically involves checking the wiring or replacing the thermistor.
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Tools You'll Need

How to Fix Error Code PB

  1. Turn Off Power and Inspect Wiring

    Always disconnect power before opening the unit to avoid electric shock.

  2. Test the Thermistor Resistance

  3. Replace the Faulty Thermistor

    Do not use electrical tape alone; moisture can cause repeated failure.

  4. Clear the Error Code and Test

Parts You May Need

10kΩ NTC Thermistor (generic)
Check Price on Amazon
Waterproof Wire Connectors
Check Price on Amazon
10kΩ NTC Thermistor (generic)
Check Price on Amazon
Waterproof Wire Connectors
Check Price on Amazon
10kΩ NTC Thermistor (generic)
Check Price on Amazon
Waterproof Wire Connectors
Check Price on Amazon
10kΩ NTC Thermistor (generic)
Check Price on Amazon
Waterproof Wire Connectors
Check Price on Amazon
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When to Call a Professional

If the thermistor tests good but the error persists, the issue may be on the control board. Call a qualified HVAC technician to diagnose board-level faults or replace the main PCB.

Frequently Asked Questions

What does error code PB mean on a Mitsubishi mini split?
Error code PB means a short circuit in the outdoor coil thermistor 2. The thermistor is a temperature sensor that monitors the outdoor coil; a short causes the system to shut down.
Can I fix Mitsubishi error code PB myself?
Yes, if you are comfortable with a multimeter and basic wiring. You can test and replace the thermistor yourself. However, if the board is faulty, call a pro.
How much does it cost to fix error PB on a Mitsubishi mini split?
DIY fix: $10-$30 for a replacement thermistor and connectors. Professional repair: $150-$300 including labor and parts.
Where is the outdoor coil thermistor located?
The thermistor is usually clamped to the outdoor coil tubing inside the outdoor unit, near the service valve area. It looks like a small metal sensor with two wires.
Will error PB clear automatically after fixing?
Yes, once the short is resolved, power cycling the unit often clears the error. If not, check connections or perform a manual reset.

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