Mitsubishi Mini Split Error Code P4: How to Fix It

Q: What does error code P4 mean on a Mitsubishi mini split?

Error code P4 indicates a drain sensor abnormality, usually caused by a clogged, frozen, or faulty drain system.

Q: Can I run my Mitsubishi mini split with error P4?

No, running the unit with a drain error can cause water damage. It's best to turn off the system and fix the issue first.

Q: How do I reset Mitsubishi mini split error P4?

After fixing the drain issue, turn off the breaker for 30 seconds, then turn it back on. The error should clear. If not, call a technician.

Q: Where is the drain sensor on a Mitsubishi mini split?

The drain sensor is a float switch located inside the indoor unit near the drain pan. Remove the front panel and filter to access it.

Q: What causes the drain sensor to go bad?

Common causes include debris buildup, stuck float, electrical failure, or freezing. Regular cleaning can prevent issues.

Abstract

Error code P4 on your Mitsubishi mini-split means the drain sensor has detected an abnormal condition, usually a clogged or frozen drain line. This can cause water to leak from the indoor unit. Follow these steps to diagnose and fix the issue.