Mitsubishi Error Code P4: Drain Sensor Error
Warning: Your Mitsubishi HVAC system has detected a potential water leak and has shut down to prevent damage. Call a professional for repair.
LED Blink Pattern
How to Fix Mitsubishi Code P4
- Check for and clear any clogs in the condensate drain line
- Inspect the drain pan for signs of water buildup
- If water is present, call a professional HVAC technician
How to Reset Mitsubishi Code P4
- Turn off the unit using the remote control or wall controller.
- Turn off the circuit breaker for the outdoor and indoor units. Wait 60 seconds.
- Restore power at the breaker.
- Turn the unit on with the remote control. If the error returns, the fault needs professional diagnosis.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Mitsubishi Error Code P4 Mean?
The P4 error code on your Mitsubishi HVAC system indicates a fault with the drain sensor. This sensor is responsible for detecting water buildup in the condensate pan. When it malfunctions, it can cause your system to shut down to prevent water damage. The most common causes for this error are a clogged drain line or a faulty sensor.
Common Causes
- Clogged condensate drain line
- Faulty drain sensor
- Incorrect sensor installation
- Water pressure issue
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Water is present in the drain pan | Inspect the drain line for clogs | Clear drain line |
| Drain line is clear | Measure voltage at the drain sensor terminals | Approximately 24V AC (normal operating voltage) |
Applicable Mitsubishi Models
- City Multi (VRF)(electric)
- City Multi (Y)(electric)
- Diamond (PJ)(electric)
- Diamond Plus(electric)
- Diamond Series(electric)
- Ducted Systems(electric)
- M-Series(electric)
- MSZ(electric)
- MSZ Series(electric)
- MSZ-AP(electric)
- MSZ-AP Series(electric)
- MSZ-AP5 Series(electric)
- MSZ-AS(electric)
- MSZ-FD(electric)
- MSZ-FE(electric)
- MSZ-FS(electric)
- MSZ-FS/FD Series(electric)
- MSZ-FT(electric)
- MSZ-FY(electric)
- MSZ-GE(electric)
- MSZ-LV(electric)
- MUZ-FE Series(electric)
- P-Series(electric)
- PUMA(electric)
- PUMY(electric)
- Puff (P-Series)(electric)
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Drain Sensor | 53015-24000 | — | Find Part |
| Condensate Drain Line | — | — | — |
Related Codes on Same Models
Other codes that affect the same Mitsubishi model families as P4.
| Code | Description | Severity |
|---|---|---|
| 1 | Indoor/Outdoor Mismatch | Warning |
| 2 | Power Supply Phase Error | Warning |
| 3 | Communication Error | Warning |
| 4 | Inverter Error | Warning |
| 5 | Outdoor Thermistor Open/Short | Warning |
| 6 | Indoor Freeze/Overheat | Warning |
| 7 | Outdoor Freeze/Overheat | Warning |
| E6 | Indoor/Outdoor Communication Error | Warning |
| E9 | Indoor/Outdoor Communication Fault | Warning |
| P1 | Intake Sensor Error | Warning |