Mitsubishi Electric Mini-Split Code E7
Soft lockout
Indoor/outdoor unit communication error (transmitting error). The indoor controller board transmitted a '0' but a '1' was read back 30 times in a row, so the indoor unit cannot reliably send to the outdoor unit.
Manual wording: “Indoor/outdoor unit communication error (Transmitting error) - Abnormal if 1 receiving is detected 30 times continuously though indoor controller board has transmitted 0.”
Documented for: A-Control indoor and outdoor units (M-Series and P-Series)
Likely causes, most common first
- Defective transmitting/receiving circuit of the indoor controller board
- Noise has entered the power supply
- Noise has entered the outdoor control wire
What you can safely check yourself
- Turn the system off at the breaker, wait one minute, and turn it back on once
When to call a technician
The manual's remedy is to power cycle and, if it repeats, replace the indoor controller board. Call a technician.
A Mitsubishi Electric mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Indoor Unit Service Manual No. OCH761 Revised Edition-A - PKA-A LA Series (May 2021) (Mitsubishi Electric, PKA-A12LA, PKA-A18LA, PKA-A12LA.TH, PKA-A18LA.TH wall-mounted indoor units) · checked 2026-08-25
- Service Manual No. OCH750 Revised Edition-E - PUZ-HA Outdoor Units (May 2024) (Mitsubishi Electric, PUZ-HA24NHA1, PUZ-HA30NKA, PUZ-HA36NKA, PUZ-HA42NKA1 heat-pump outdoor units) · checked 2026-08-25