Mitsubishi Electric Mini-Split Code E5
Soft lockout
Remote controller transmitting error detected by the indoor unit. The indoor controller board could not find a free slot on the transmission path, or its sent and received data disagreed 30 times in a row.
Manual wording: “Abnormal if indoor controller board could not find blank of transmission path. (Check code: E5)”
Documented for: A-Control systems with a wired remote controller
Likely causes, most common first
- Two remote controllers both set as 'main'
- One remote controller connected to 2 or more indoor units
- Repetition of refrigerant address
- Defective transmitting/receiving circuit of the indoor controller board or remote controller
- Noise has entered the remote controller transmission 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
Diagnosing the remote controller and the indoor board is a technician task.
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