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Mitsubishi Electric Air Conditioner U6 / UP / UF Error Code
Compressor overcurrent. Here is what it means and how to clear it, easiest fix first.
The outdoor unit cut power to the compressor because it drew too much current. UF means the compressor appears locked at start-up; U6 can also indicate a problem with the inverter's power module.
These codes appear on outdoor units used with Mr. Slim and P-series systems; exact meanings vary by series, so check your manual.
How to fix Mitsubishi Electric U6 / UP / UF
Reset the power at the breaker
Switch off the breaker that feeds the air conditioner (some systems have separate breakers for the indoor and outdoor units, so switch off both). Wait about five minutes, switch the power back on and restart the unit to see if the code clears.
Don't keep restarting it
If the code returns quickly, leave the system off. Repeated restarts against a locked or faulty compressor can cause more damage.
When to call a technician
Compressor and inverter faults involve high-voltage parts in the outdoor unit, so book a technician.
Parts that commonly cause U6 / UP / UF
- compressor
- inverter PCB
- power module
Order parts by your exact model number so they fit.
Other Mitsubishi Electric air conditioner codes
- Blinking OPERATION lightWall unit's indicator light is flashing
- P1Room air temperature sensor fault
- P2 / P9Indoor coil temperature sensor fault
- P4 / P5Drain sensor or drain pump problem
- PAShut down to prevent a water leak
- P6Freeze or overheat protection
- P8Pipe temperature error
- PbIndoor fan motor error
- FbIndoor control board error
- E0-E5Wall controller communication error
- E6 / E7 / E9Indoor and outdoor units aren't communicating
- U1 / UdHigh pressure or overheat protection
- U2Discharge temperature too high or low refrigerant
- U3 / U4Outdoor temperature sensor fault
- U8Outdoor fan stopped
- U9 / UHPower supply or current sensor problem
- PLRefrigerant circuit abnormal
Frequently asked questions
What does U6 / UP / UF mean on a Mitsubishi Electric air conditioner?
The outdoor unit cut power to the compressor because it drew too much current. UF means the compressor appears locked at start-up; U6 can also indicate a problem with the inverter's power module.
Can I fix Mitsubishi Electric U6 / UP / UF myself?
Only the basic checks. You can safely try the steps above, but U6 / UP / UF usually points to a part or fault that needs a technician.
What if U6 / UP / UF keeps coming back?
A code that returns after a reset and the checks above usually means a part is wearing out. Note when U6 / UP / UF appears (which cycle, how often) and have your model number ready; it helps a technician bring the right part on the first visit.
Last reviewed 2026-10-19. Codes and steps can vary by model; check your owner's manual.