P4 - The drain sensor is reporting a fault.
Mitsubishi Electric's PEAD installation manual lists P4 as a drain sensor error. This indicates the condensate monitoring circuit has detected an abnormal drain-sensor condition.
Applies to the PEAD-M50-140JAA installation-manual family; drainage hardware layout can vary by installation.
Severity
High
Display
Shown as check code P4 on the wired remote controller. On supported self-check patterns, four beeps/flashes map to P4.
Support first?
Often not
Models in range
PEAD-M50JAA(D), PEAD-M60JAA(D), PEAD-M71JAA(D)
What to do first
Start with these checks
- 1Turn the system off to avoid possible condensate overflow.
- 2If safe and accessible, look for obvious water leakage around the indoor unit or ceiling grille.
- 3Book service if the code does not clear after restart.
Likely causes
What usually sits behind this code
Drain sensor fault
Wiring issue to the drain sensor
Drainage problem causing abnormal condensate detection
Contact support
Contact customer support if any of these apply
- !P4 appears with water leakage or staining
- !The unit stops cooling and the code remains
- !The code returns after one restart attempt
- - The official table labels P4 as 'Drain sensor error'.
- - Drain-related faults should be handled promptly to reduce water-damage risk.
Related codes
Nearby codes in this family
More ranges
More Mitsubishi Electric air-conditioner ranges
Source notes
Source and scope
Source: Mitsubishi Electric Australia installation manual
The PEAD-M50-140JAA installation manual lists P4 in the check-code table as 'Drain sensor error'.
Last reviewed: 2026-04-19
The code meaning is official, but confirming whether the issue is the sensor, wiring, or a drainage condition requires inspection.