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ErrorLib — Industrial Fault Code Library

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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. 1

    Verify the connecting wire between the indoor unit and remote controller is connected correctly at both ends.

  2. 2

    Inspect the transmission wire of the remote controller for signs of electrical noise interference.

  3. 3

    Cycle power to the unit (turn off, then on again) to re-check for the error.

Browse all codes in this manual (26)
Verified technical data. Last updated: April 2026

Related Faults

----No Error History00Communication Error (Indoor/Outdoor/Remote Controller)A0~A8M-NET System Communication Error
Source: Mitsubishi Electric PAR-21MAA MA Remote Controller
Open Manual (Page 48)Search more codes in this manual