EF
Remote Controller Transmit Error (Indoor Unit Side)
Mitsubishi Electric · PAR-21MAA MA Remote Controller
What does EF mean?
The indoor unit has detected an error in transmitting signals to the remote controller. This suggests a problem with the indoor unit's communication circuit or the wiring between the indoor unit and the remote controller, preventing it from sending status updates or acknowledgments.
Common Causes
- Indoor unit fails to transmit signals to the remote controller.
- Faulty indoor unit's remote controller interface circuitry.
- Communication bus issues on the indoor unit side.
- Power supply issue to the indoor unit's communication components.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Verify the connecting wire between the indoor unit and remote controller is connected correctly at both ends.
- 2
Inspect the transmission wire of the remote controller for signs of electrical noise interference.
- 3
Cycle power to the unit (turn off, then on again) to re-check for the error.
Verified technical data. Last updated: March 2026
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Source: Mitsubishi Electric PAR-21MAA MA Remote Controller