Mitsubishi · Mini-split
P4 Condensate drain problem
What this code means
The condensate pump isn't working or the drain line is blocked, risking a water overflow.
Most likely causes
- Clogged condensate drain line
- Failed condensate pump
What to try first
Check the drain line exit outside for blockage; a wet/dry vac at the outdoor end can sometimes clear it.
Good news: this one is often fixable without a service call. If it persists after the steps above, have it looked at.
Find the part on Amazon →FAQ
What does Mitsubishi error code P4 mean?
Condensate drain problem. The condensate pump isn't working or the drain line is blocked, risking a water overflow.
Can I fix Mitsubishi code P4 myself?
Often, yes. Check the drain line exit outside for blockage; a wet/dry vac at the outdoor end can sometimes clear it.
What causes Mitsubishi code P4?
The most common causes are: clogged condensate drain line; failed condensate pump.
Other Mitsubishi mini-split codes
All Mitsubishi mini-split error codes →
Other mini-split brands: Daikin · LG · Fujitsu · Gree · Carrier · Generic · Panasonic
This information may contain errors or not apply to your exact model — always double-check it against your appliance's own manual before acting. If there's any chance of a gas, fire, electrical, carbon monoxide, or other safety hazard, stop and call a licensed professional or the appropriate agency (e.g. your gas utility) instead of relying on this page alone.