Mitsubishi Electric mini split error code P5
Drain pump fault (overflow protection).
- TypeFault
- SystemCondensate drain
- Can I fix it?Homeowner checks, then maybe a tech
What P5 means on a Mitsubishi Electric
The drain pump ran but the water level did not drop, or the pump is not running at all.
On this platform, P5 is a fault: something has failed or is disconnected and needs diagnosis.
Common causes
- A blocked drain line after the pump.
- A failed pump motor.
- A loose pump connector.
How to fix it yourself
Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician.
- Clear the drain line downstream of the pump.
- With power off, reseat the pump connector.
- Listen for the pump running when the unit cools.
Switch off power at the breaker before opening either unit. Capacitors in the outdoor unit hold a charge for several minutes after power is cut.
When to call a technician
Pump replacement by a technician if it does not run.
Which Mitsubishi Electric units show P5
This page applies to Mitsubishi Electric M-Series (MSZ), Mr. Slim (PKA/PCA), Hyper-Heating H2i and MXZ multi-zone units. Mitsubishi Electric's own documentation lists P5 as "Drain pump fault (overflow protection)", the same definition used across the Mitsubishi Electric it is built on. If your unit shows a code with a different shape (for example a four-character code, or a plain number), it is from a different table; use the lookup with your exact code.
Where Mitsubishi Electric shows this code
Wall units without a wired controller signal a fault by blinking the operation indicator lamp; the code itself shows on a wired controller (MHK/PAR series) or on the wireless remote after entering its check mode (see your manual). On the outdoor unit, the control board LEDs blink the same code. P codes are indoor-unit faults, E codes are communication faults, F codes are outdoor-unit faults and U codes are outdoor-unit and compressor faults.
Other Mitsubishi Electric codes
Same part of the system as P5:
P5 on other brands
The same characters do not always mean the same thing. Check the brand on your unit.
- Pioneer P5 Mode conflict (multi-zone) / Condenser high temperature protection (outdoor display)
- Blueridge P5 Compressor current protection / Mode conflict (multi-zone)
- Gree P5 Compressor current protection
- Zone Air P5 Cooling mode sub-cooling (anti-freeze) protection
- Carrier P5 Mode conflict (multi-zone)
- Trane P5 Cooling mode sub-cooling (anti-freeze) protection / Drain pump fault (overflow protection)
- Heil P5 Mode conflict (multi-zone) / Compressor current protection
- ACiQ P5 Mode conflict (multi-zone) / Cooling mode sub-cooling (anti-freeze) protection
Questions people ask
Can I reset a Mitsubishi Electric P5 code myself?
Yes. Turn the system off at the breaker for five minutes, then restart it. If P5 comes back, the fault is real and needs the checks above.
Is it safe to keep running a Mitsubishi Electric showing P5?
The unit will usually refuse to run, or run with reduced output, until the fault is cleared. Repeated resets do not fix anything and can mask a problem that is getting worse.
Do I need a technician for Mitsubishi Electric P5?
Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician. Pump replacement by a technician if it does not run.
Sources
- Mitsubishi Electric M-Series and Mr. Slim service manuals (self-diagnosis tables)
Updated September 2026. Codes and definitions vary by model year. If your manual disagrees with this page, your manual wins. Send a correction.