Mitsubishi Electric Mini-Split E6 Error Code: What It Means and How to Fix It

By Dan Mercer · Published October 5, 2026 · Updated October 6, 2026 · Codes covered: E6, E7 · Sources

Verify in your manual: Meaning taken from the MSZ-GX / MSY-GX (R-454B) operating instructions (Mitsubishi Electric Canada copy and a US retailer copy). Other series, wired remotes and US manuals may word it differently or use other codes; check your own manual.

E6 on a Mitsubishi Electric mini-split means the indoor unit has a serial signal problem: it isn't hearing the outdoor unit properly. You can safely rule out a few simple things, like a tripped breaker or a power glitch, but Mitsubishi's own instruction for any error code is to stop using the unit and call your dealer. E7 is listed with the same meaning.

This 3-minute fix saved 0 homeowners a technician visit this month.

What the E6 code means

In the operating instructions for the current MSZ-GX and MSY-GX wall-mounted units (R-454B refrigerant), the "Error code of remote controller" table lists E6 and E7 together under the indoor unit, with the abnormal point "Serial signal". The serial signal is the data link between the indoor and outdoor units, so in plain terms E6 is a communication error seen from the indoor side.

Which models this covers: the table appears in the operating instructions for MSZ-GX06NL, GX09NL, GX12NL and GX15NL, and MSY-GX09NL, GX12NL and GX15NL. Mitsubishi Electric Canada publishes the Canadian version, and a US retailer (HVACDirect) hosts the US version. The two tables match. Older Mitsubishi owner's manuals (for example MSZ-GL) don't include a code table at all, and wired remotes and ducted or cassette units can show different codes. If you have another series, check your own manual or ask your dealer before relying on this meaning.

How you see the code on MSZ-GX units: the unit doesn't show E6 on its own. When something is wrong, the left/upper operation lamp on the indoor unit blinks. Then:

1. Turn the remote off.
2. Point it at the indoor unit and keep pressing the small CHECK button with a fine-tipped object (a pen tip works) until the unit beeps. "00" shows on the remote.
3. Step through the codes with the temperature up and down buttons. The indoor unit beeps twice when the code on the remote matches the stored error, and once if it doesn't.

Mitsubishi notes that if you do this while the lamp isn't blinking, "the accurate error code might not be shown."

Look-alike codes: E8, E9 and EC are listed separately, under the outdoor unit, as "Indoor/outdoor communication, receiving error." They point to the same link but from the other end. See our Mitsubishi Electric E9 page.

Likely causes (most common first)

Mitsubishi's table names the abnormal point but doesn't list causes. Here's what typically sits behind a serial signal fault, starting with what you can check.

1. A power interruption or surge. A storm, outage or tripped breaker can upset the link between the units. Mitsubishi tells owners to turn the breaker off when lightning is possible because "the unit may be damaged if lightning strikes."
2. The outdoor unit has no power. If its breaker or disconnect is off or tripped, the indoor unit can't hear it.
3. A wiring or connection problem between the indoor and outdoor units (the connecting cable that runs with the refrigerant lines). This is a job for an installer.
4. A control board or other electrical fault in either unit. This needs a technician.

How to fix it, step by step

Mitsubishi's manual is clear: "When the unit has an error, the air conditioner needs to be inspected and repaired. Stop using the air conditioner, turn off the breaker and contact your dealer." The steps below are safe things to check and note before or while you arrange service. None of them involve opening a panel.

1. Write down the code. Use the CHECK procedure above and note whether it's E6 or E7, plus anything that happened just before (a storm, outage, or electrical work).
2. Stop the unit with the remote first. Mitsubishi warns: "Do not turn the breaker OFF/ON or disconnect/connect the power plug during operation." Always switch the unit off with the remote before touching the breaker.
3. Turn off the breaker. This follows Mitsubishi's instruction for any error code.
4. Check that the breakers are really on (if you plan one restart). Look at your panel for a tripped breaker for the indoor or outdoor unit, and check the outdoor disconnect switch if you have one. A tripped breaker is the most common simple reason a unit can't talk to its partner.
5. Try one restart only if the code came right after a storm or outage. Mitsubishi doesn't list a reset for error codes. Still, one restart is a reasonable step for a homeowner: leave the breaker off for a few minutes, switch it back on, and start the unit with the remote. The unit may not run for about 3 minutes after a restart, which Mitsubishi says is normal ("Please wait.").
6. If the lamp blinks again, stop. Turn the unit off with the remote, switch off the breaker, and call your dealer. Don't keep cycling the power.
7. Don't open anything. Don't open the outdoor unit or touch the wiring between the units. Mitsubishi says the unit "should not be installed, relocated, disassembled, altered, or repaired by the user."

Test the part

There's no safe owner meter test for a serial signal fault. The parts involved are the interconnecting cable and control boards, which sit behind panels with live, high-voltage parts. These visual checks are all you should do:

1. Unplug the power first: switch the system off. Mini-splits are usually hard-wired. Stop the unit with the remote, then switch off its breaker and the outdoor disconnect if there is one.
2. Look at the breaker panel. Note any breaker that was tripped. If a breaker trips again after you reset it, leave it off and call a pro. Mitsubishi lists "When the breaker trips frequently" as a reason to call your dealer.
3. Walk around the outdoor unit. Look for obvious damage: a chewed or crushed cable, a damaged line-set cover, storm debris, or water pooling around the electrical box. Look only. Don't touch or move the cable.
4. Check the remote. If the remote display is dim or blank, Mitsubishi asks "Are the batteries exhausted?" New batteries won't fix E6, but you need a working remote to read the code.
5. Stop there. Testing the cable or boards means measuring live voltage, which is for a licensed HVAC technician only.

Safety notes

When to call a pro

Call your Mitsubishi Electric dealer or installer if:

• the lamp blinks again and E6 or E7 comes back after one restart
• a breaker for the system trips again
• you see damage to the cable or line set outdoors
• the unit was recently installed, moved or worked on (wiring is a common suspect then)
• the unit is under warranty. Mitsubishi says repairs should go through your dealer.

Have your model numbers (indoor and outdoor), the code, and when it started ready.

FAQ

Related

• Mitsubishi Electric Air Conditioner E9 Error Code
• Mitsubishi Electric Air Conditioner P8 Error Code
• Cooper & Hunter Air Conditioner dF Error Code
• Cooper & Hunter Air Conditioner EC Error Code
• Daikin Air Conditioner A5 Error Code
• Daikin Air Conditioner EA Error Code
• All air conditioner error codes