HVAC Code Lookup

Mitsubishi Electric Mini-Split Code E6

Soft lockout

Indoor/outdoor unit communication error (signal receiving error). The indoor controller board received no signal from the outdoor unit for 6 minutes after power-on, or for 3 minutes during operation. The most common cause is a problem with the wire running between the indoor and outdoor units.

Manual wording: “Indoor/outdoor unit communication error (Signal receiving error) - Abnormal if indoor controller board cannot receive any signal normally for 6 minutes after turning the power on.”

Documented for: A-Control indoor and outdoor units (M-Series and P-Series)

Likely causes, most common first

  1. Contact failure, short circuit or miswiring (reverse wiring) of the indoor/outdoor unit connecting wire
  2. Defective transmitting/receiving circuit of the indoor controller board
  3. Defective transmitting/receiving circuit of the outdoor controller board
  4. Noise has entered the indoor/outdoor unit connecting wire

What you can safely check yourself

  • Check that the breaker feeding the outdoor unit is on and has not tripped
  • Check that the outdoor unit is clear of snow, ice and debris and that nothing has damaged the wire cover
  • Turn the system off at the breaker, wait one minute, and turn it back on once

When to call a technician

The S1-S2-S3 connecting wire carries line voltage. Checking, tightening or correcting it, and any board replacement, is a technician job.

A Mitsubishi Electric mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other Mitsubishi Electric codes