Mitsubishi Electric Mr. Slim PLA Series Service Manual page 25

Abnormal point and detection method
Check code
Remote controller transmission
error(E3)/signal receiving error(E5)
1
2
1
2
Indoor/outdoor unit communication
error (Signal receiving error)
1
2
3
Indoor/outdoor unit communication
error (Transmitting error)
Indoor controller board
Remote controller control board
1
2
Abnormal refrigerant circuit
These detected errors will not be
cancelled until the power source is
reset.
OCH581
Cause
1
2
3
4
5
6
1
2
3
4
1
2
3
1
1
Countermeasure
1
2
3
4–6
1
2–4
1–3
1
1
When this error occurs, be sure to
replace the 4-way valve.
To avoid entry of moisture or air into
refrigerant circuit which could cause
abnormal high pressure, purge air in
refrigerant circuit or replace refrigerant.