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Mitsubishi Electric Air Conditioner P1 Error Code

Room air temperature sensor fault. Here is what it means and how to clear it, easiest fix first.

P1
May need a pro

The indoor unit's intake (room air) temperature sensor, labeled TH1 in Mitsubishi Electric documents, is giving an abnormal reading. The sensor itself, its connector or the indoor board may be at fault.

These check codes appear on wired wall controllers, mainly with P-series, Mr. Slim and ducted or ceiling units; wall-mounted M-series units (MSZ) usually report faults by blinking the OPERATION light instead. The meanings here come from Mitsubishi Electric's Mr. Slim code list for Singapore models and its North American wired-controller manual, and they can differ by series and region, so check your manual.

Safety first: unplug the air conditioner (or switch off its breaker) before touching filters, hoses or panels. If you smell burning or gas, or see water near the outlet, stop and call a professional.

How to fix Mitsubishi Electric P1

  1. 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.

  2. Note the full code and model number

    If the code returns, write down exactly what the display shows on the wall controller and the model number from the label on the side of the indoor unit. Sensor and board parts differ between models, so this lets the technician bring the right part on the first visit.

When to call a technician

If P1 returns, a technician needs to test the sensor and indoor control board.

Parts that commonly cause P1

Order parts by your exact model number so they fit.

Other Mitsubishi Electric air conditioner codes

Frequently asked questions

What does P1 mean on a Mitsubishi Electric air conditioner?

The indoor unit's intake (room air) temperature sensor, labeled TH1 in Mitsubishi Electric documents, is giving an abnormal reading. The sensor itself, its connector or the indoor board may be at fault.

Can I fix Mitsubishi Electric P1 myself?

Only the basic checks. You can safely try the steps above, but P1 usually points to a part or fault that needs a technician.

What if P1 keeps coming back?

A code that returns after a reset and the checks above usually means a part is wearing out. Note when P1 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.

References