E9
Outdoor Unit Communication Receive Error
Mitsubishi Electric · PAR-21MAA MA Remote Controller
What does E9 mean?
The outdoor unit has detected an error in receiving communication signals from the indoor unit. This indicates a problem with the data transmission path from the indoor unit or the outdoor unit's receiving circuit, leading to a loss of outdoor unit control.
Common Causes
- Outdoor unit fails to receive valid data packets from the indoor unit.
- Communication cable issue (open, short, noise) between indoor and outdoor units.
- Faulty communication receiver chip on the outdoor unit PCB.
- Indoor unit not transmitting data correctly or at all.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Verify the indoor/outdoor connecting wire terminations match the wiring diagram for correct connection.
- 2
Inspect the indoor/outdoor connecting wire and power supply for signs of electrical noise interference that could disrupt signal reception.
- 3
Cycle power to the unit (turn off, then on again) to re-check for the error.
Verified technical data. Last updated: March 2026
Related Faults
Source: Mitsubishi Electric PAR-21MAA MA Remote Controller