Mitsubishi P6 Error Code: Current Transformer Sensor Fault

Quick Answer

A Mitsubishi P6 error indicates a current protection fault where the CT sensor detects an overcurrent condition. The primary fix is to check for power supply issues or a faulty outdoor control board after ensuring the coils are clean.

When I show up to a P6 call, the outdoor unit is usually either filthy or starting to fail electrically. This code is the system protecting itself before a $1,500 compressor turns into scrap metal. Ignore it and keep resetting and you'll probably end up replacing the whole outdoor unit. Worth getting a tech out to check the CT sensor and compressor amps before you decide anything.

MitsubishiMinisplitSeverity: highDifficulty: advanced65% DIY Success

Time to Fix

60–240 min

Difficulty

advanced

Parts Cost

$30 – $80

Tools Needed

Phillips #2 screwdriver, Flathead screwdriver (for panel clips)

What Does the P6 Code Mean?

The P6 code is basically Mitsubishi's way of saying something's drawing way too much power out there and it's not going to let it burn itself up. The current transformer sensor watches the amperage going to the compressor, and if it spikes past the limit, the whole system shuts down. It's usually a dirty coil, a weak compressor, or a bad sensor. I checked three of these last week and two were just filthy condensers.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

CT sensor failure on outdoor unit40%

Compressor drawing abnormal current24%

Outdoor unit PCB fault22%

Wiring fault at CT sensor connection14%

Symptoms You May Notice

The indoor head unit shows P6 and the system shuts down completely, sometimes within 30 seconds of startup.
You hear the outdoor unit hum for a second or two and then go completely silent while the error code appears on the display.
There's a loud buzz or clicking sound from the outdoor unit right before it trips off, usually the compressor trying and failing to start.
Outdoor fan spins normally but the compressor never fully engages, or engages for just a second and then cuts out.
System was cooling fine for years and then suddenly quit with no gradual decline or warning signs beforehand.

Can you reset a Mitsubishi minisplit to clear the P6 code?

Go to your electrical panel and flip the breaker for the outdoor unit off. Wait a full 60 seconds, not 10, not 30. The inverter board capacitors need that full minute to discharge. Flip it back on and set the thermostat to call for cooling. Watch the display for the next 5 minutes. If P6 comes back before the unit gets to temp, turn it off and leave it alone until a tech can check it.

Tools Required for Diagnosis

Phillips #2 screwdriverFlathead screwdriver (for panel clips)Clamp meter (for live amperage testing)Multimeter (for CT sensor resistance and voltage checks)Non-contact voltage testerRefrigerant manifold gauge set (EPA 608 certified, technician only)Work gloves (sheet metal edges are sharp)

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name	OEM Number	Estimated Price
CT Sensor (current transformer)T7WE17200 (verify for your model) · $30–$80	T7WE17200 (verify for your model)	$30 – $80

Frequently Asked Questions

What is a CT sensor on a mini-split?

It's basically a tiny watchdog for your compressor's electricity. It's a small ring that clamps around the power wire leading to the compressor and uses magnetism to measure how much current is flowing, without even touching the wire directly. If the compressor starts pulling more amps than it's supposed to, because it's wearing out or the coil is filthy and it's working too hard, the CT sensor tells the board to cut power before something melts or catches fire.

Why shouldn't I keep resetting a P6 error?

Because you'll kill the compressor, honestly. Think of it like a fuse that keeps blowing. If you keep replacing the fuse without fixing the short, eventually something burns up. The P6 is the warning. Force a struggling compressor to try and start over and over and you'll overheat the motor windings. A $150 CT sensor fix can turn into a $1,500 compressor replacement or a whole new outdoor unit real fast if you keep forcing resets.

Can low refrigerant cause a P6 error?

Yeah, absolutely. When the system's low on refrigerant, the compressor has to spin faster and work way harder to hit your target temperature. That extra strain pushes the amp draw up. Eventually it climbs past the threshold the CT sensor is watching for, and it trips the P6 fault. I always check refrigerant pressures before I condemn a CT sensor or a board, because low refrigerant is sneaky and causes a ton of weird error codes that look like electrical problems.

How much does CT sensor replacement cost?

If it's just the sensor, you're usually looking at $150 to $350 total with the service call, depending on your area. The part itself is often under $50. But here's the thing, if the sensor tests fine and the compressor is actually drawing high amps because it's worn out internally, that changes everything. On a unit that's 10+ years old I'll usually tell you to get quotes on a new outdoor section before spending money on a board or compressor repair. The math rarely works out.

My Mitsubishi mini-split shows P6 only when it's very cold outside. What does that mean?

That's a pretty specific clue, actually. In cold weather the heat pump works at maximum capacity to pull heat from frigid outside air, and that drives up the electrical demand on the compressor. If there's any weakness in the system, a slightly low refrigerant charge, a compressor that's starting to wear, a borderline CT sensor, that cold weather stress test is exactly when it'll trip. If it only happens below 30°F or so, get your refrigerant pressures checked first thing.

Related Mitsubishi Minisplit Error Codes

Code: HUBMitsubishi Mini-Split Error Codes: Complete MSZ and MXZ Series Guide Code: RESETMitsubishi Mini-Split Error Codes: Complete MSZ and MXZ Series Guide

Models Known to Experience P6 Errors

This repair applies to most Mitsubishi minisplits with this error code. Common model numbers include:

MSZ-GL09NA, MSZ-GL12NA, MSZ-GL18NA, MSZ-FH09NA, MSZ-FH12NA, MSZ-FS12NA, MXZ-2C20NAHZ, MUZ-GL12NA

Written by

Raj Patel

HVAC & Water Systems Specialist · 15 years experience

Last verified for technical accuracy on March 14, 2026