Mitsubishi Electric FB

Medium

PLY-ZM/PLY-M/PEY-M/PCY-M serisi — Indoor unit control system error (memory error, etc.)

Mitsubishi Electric FB: Indoor unit control system error (memory error, etc.) This fault usually isn't an immediate stop, but should be checked soon.

Possible causes

Faulty memory chip or firmware fault on the control board
Voltage spike/power disturbance affected the control board

Check steps

Power cycle the unit to reset the control board
If error persists, replace the indoor controller board

Affected parts

Indoor controller board

Safety note

Disconnect power supply before replacing the control board.

Source: Mitsubishi Electric resmi servis kilavuzu (bagimsiz cift-dogrulandi) — Mitsubishi Electric Mr. SLIM Indoor Unit — Malfunction-diagnosis method at maintenance service, rev. 20241024, applicable to PLY-ZM50EA / PLY-M60,80,100,125EA / PEY-M50,60,80,100,125JAL / PCY-M125KAL, page 3, [Output pattern A] table: "FB(Fb) | Indoor unit control system error (memory error, etc.)" (12 beeper sounds/…

Reviewed by Anıl Güzeldemir — in the refrigeration machine room since 2006, developer of Enthalio.

Look up in Enthalio →

Related fault codes

Communication error between wired remote contrE5 Combination error between indoor and outdoor uEE Forced compressor error (due to water leakage PA Indoor unit fan motor errorPB Indoor/outdoor communication error.E6 High discharge temperature — compressor overheU2