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ErrorLib — Industrial Fault Code Library

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U8 (00)

Current Sensor Error / Outdoor Fan Motor Anomaly

Mitsubishi Electric · PUZ-HA30/36NHA4 Outdoor Unit

What does U8 (00) mean?

This code indicates either an abnormal current detection by the current sensor (-1.5A to 1.5A) during compressor operation, or an abnormal rotational frequency of the outdoor fan motor. Fan motor abnormality occurs if rotation is below 100 rpm for 1 second at >=20°C ambient temperature, or below 80 rpm / above 1300 rpm continuously for 1 minute. Potential root causes include incorrect compressor wiring, a defective current sensor circuit on the outdoor power circuit board, DC fan motor failure, or an issue with the outdoor circuit controller board.

Common Causes

  • Current sensor fault or anomaly detected (U8 code).
  • Outdoor fan motor operating outside expected parameters or has an internal fault.
  • Interference or signal loss from the outdoor fan motor control.
  • Possible issue with the outdoor fan motor's speed or direction feedback.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Correct the U·V·W phase wiring to the compressor. Refer to section 10-9 for the Outdoor power circuit board.

  2. 2

    Check or replace the DC fan motor.

  3. 3

    Check the voltage of the outdoor circuit controller board during operation.

  4. 4

    Replace the outdoor power circuit board if the current sensor issue persists after verifying wiring.

  5. 5

    Replace the outdoor circuit controller board if the fan motor failure persists after checking/replacing the motor.

Browse all codes in this manual (45)
Verified technical data. Last updated: April 2026

Related Faults

01Overvoltage Error02Undervoltage Error04L1 or L2-Phase Open Error
Source: Mitsubishi Electric PUZ-HA30/36NHA4 Outdoor Unit
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