Mitsubishi Electric UH error code

What it means

UH means a control-board memory, voltage, or feedback signal is outside the normal range. That does not tell a homeowner which board is bad; it tells you the controls are no longer confident enough to run normally. Treat a repeat code as a service diagnosis. Manual trigger: Each phase current of the compressor cannot be detected normally.

Urgency

Likely causes

1. Brief power event, brownout, or unstable supply voltage
2. Loose power connection, reactor, or outdoor electrical component problem
3. Inverter/IPM protection or current-detection fault
4. Compressor winding, drive, or outdoor board fault after power checks pass

Homeowner fix

Power cycle once and note any storm, brownout, generator, or recent electrical work. Expected result: a one-time control fault clears; if it returns, do not open the cabinet.

When to call a pro

Call a licensed HVAC technician if the code returns after one reset or you suspect a supply-voltage problem. Tell them the Mitsubishi code points to a board, relay, current, voltage, or converter circuit.

Repair vs replace

This can be a control-board repair, which is not automatically a replacement signal. Compare the quote with replacement if the unit is older, out of warranty, or has repeated board failures.

• Mitsubishi Electric M-Series GX 9,000 BTU R-454B 208/230V (MSZ-GX09NL / MUZ-GX09NL)

  M-Series GX

• Mitsubishi Electric M-Series GX Hyper-Heat 9,000 BTU R-454B 208/230V (MSZ-GX09NL / MUZ-GX09NLHZ)

  M-Series GX

• Mitsubishi Electric M-Series GX 12,000 BTU R-454B 208/230V (MSZ-GX12NL / MUZ-GX12NL)

  M-Series GX

• Mitsubishi Electric M-Series GX Hyper-Heat 12,000 BTU R-454B 208/230V (MSZ-GX12NL / MUZ-GX12NLHZ)

  M-Series GX

Parts for this line

The parts catalog for Mitsubishi Electric M-Series GX lists 6 sourced replacement parts for this product line.

For your technician

Technician note: verify incoming power, connectors, and the named P.C. board circuit before board replacement. Page context: Mitsubishi Electric maps this display to the M-Series GX line; source: Mitsubishi Electric MSZ-GX/MUZ-GX R454B service manuals; display convention: match the letter U and letter H marker exactly before comparing neighboring codes.

Which systems show it

• Mitsubishi Electric M-Series R454B wall-mount outdoor units covered by MUZ-GX OBH951C and cross-checked against MUZ-FX OBH946C and MUZ-WX OBH955A.

Related troubleshooting

Use the symptom guide alongside the exact display code if the unit is flashing, cycling, or showing comfort symptoms.

Reset note

After the documented cause is corrected, operate the unit and confirm the failure-mode recall/error-code display returns to 00.

Manual trigger

Each phase current of the compressor cannot be detected normally.

Related codes

Source

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