Mitsubishi Electric U2 Error Code: High discharge temperature or insufficient refrigerant
Updated October 2026 · Sourced from Mitsubishi Electric documentation
🛑 Turn it off and call a licensed pro
The outdoor side reports abnormal high discharging temperature, 49C operated, or insufficient refrigerant.
Is it safe to keep running? No. Turn it off and get it checked. Turn the unit off and call a licensed technician. Low refrigerant is a technician repair.
U2 at a glance
| Code / how it shows | Meaning | Applies to |
|---|---|---|
| U2 Second self-check pattern, 5 flashes | High discharge temperature or insufficient refrigerant | PLA-RP35/50/60/71/100/125/140BA ceiling cassette indoor units (Mr. Slim, OCH416 service manual) |
🛑 Stop and call a licensed pro if
- Turn the unit off and call a licensed technician. Low refrigerant is a technician repair.
- Any code pointing to refrigerant, the compressor, high pressure or the outdoor unit board. Refrigerant work legally needs a certified technician.
- Burning smell, sparks, or a breaker that trips again after a reset.
- Water leaking from the indoor unit that does not stop after the drain is clear.
Safe first steps for any Mitsubishi Electric code
- Write down the exact code and how it shows (remote display or number of lamp blinks). Similar codes mean different things on different series.
- Turn the system off at the remote, switch off the breaker or disconnect for the unit, wait a few minutes, then turn it back on.
- Clean or replace the indoor unit air filters, and make sure nothing blocks the indoor or outdoor unit.
- Check that the condensate drain line is not blocked or kinked where you can see it.
- Replace the remote controller batteries if the display is dim or the unit does not respond.
Source: Mitsubishi Electric PLA-RP BA Service Manual OCH416 Rev. D, p.22. Codes are series-specific, so your unit's own manual is the final word. Reviewed October 2026.
Shaun Cain · Certified HVAC & Refrigeration Technician · Ask an HVAC technician
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