What it means
Mitsubishi's code tables give E7 the same meaning. With a wireless remote, the self-check reports it as 3 beeps and 3 flashes of the OPERATION INDICATOR lamp (SLZ-KF and SLZ-M manuals). MSZ wall units have no code display: their service manuals describe a similar 'miswiring or serial signal' fault as the OPERATION INDICATOR lamp blinking continuously, 0.5 seconds on and 0.5 seconds off, when no signal arrives from the outdoor unit for 6 minutes.
What to check, in order
- Write down the code
Mitsubishi's operation manual asks you to note the unit number and error code shown on the controller. The engineer will want both.
- Switch off and on once
Turn the system off at the circuit breaker or isolator, then back on. Mitsubishi's service manuals use this power reset to check whether the fault comes back.
- Give it time to reconnect
Mitsubishi's PUZ-HA manual says the indoor unit allows up to 6 minutes after power-on to receive a signal before it flags E6, so wait before deciding it has failed again.
When to call an engineer
If E6 comes back after a reset, call an air conditioning engineer (UK) or HVAC technician (US). Mitsubishi lists a loose, shorted or wrongly connected indoor/outdoor connecting cable, a faulty transmit or receive circuit on a control board, and electrical noise on the cable.
Quick answers
What does the Mitsubishi E6 error code mean?
The indoor unit is not receiving a proper signal from the outdoor unit, so the system has stopped. Mitsubishi's manuals point to the cable between the units and the control boards. Mitsubishi's code tables give E7 the same meaning. With a wireless remote, the self-check reports it as 3 beeps and 3 flashes of the OPERATION INDICATOR lamp (SLZ-KF and SLZ-M manuals). MSZ wall units have no code display: their service manuals describe a similar 'miswiring or serial signal' fault as the OPERATION INDICATOR lamp blinking continuously, 0.5 seconds on and 0.5 seconds off, when no signal arrives from the outdoor unit for 6 minutes.
Can I fix Mitsubishi E6 myself?
Easy (about 10 minutes). Start with: write down the code; switch off and on once; give it time to reconnect. If E6 comes back after a reset, call an air conditioning engineer (UK) or HVAC technician (US). Mitsubishi lists a loose, shorted or wrongly connected indoor/outdoor connecting cable, a faulty transmit or receive circuit on a control board, and electrical noise on the cable.
Is Mitsubishi E6 worth repairing?
Worth fixing. One reset is worth trying. If the code returns, it is a wiring or control board fault for an engineer, not a refrigerant repair.
Checked against
- Mitsubishi Electric SLZ-KF09/12/15/18NA1 ceiling cassette (M-series) Technical & Service Manual TCH118A (PDF)
- Mitsubishi Electric SLZ-M15-60FA ceiling cassette Technical & Service Manual OCH522 (PDF)
- Mitsubishi Electric PUZ-HA30/36NHA4 outdoor unit Service Manual OCH504 (PDF)
- Mitsubishi Electric Air-Conditioners indoor unit Operation Manual BG79U581H01 (PLA, PKA, PCA, PSA, PEAD) (PDF)
- Mitsubishi Electric MSZ-FH06-18NA(2) indoor unit Service Manual OBH683E (PDF)
Last reviewed October 2026. Manufacturers update their pages, and your manual is the final word. Spotted a mistake? Email contact@appliance-error-codes.com.