Mitsubishi Error Code P4: Drain float switch disconnected (Heat Pump)
Mitsubishi error code P4 on a heat pump means: Drain float switch disconnected. It is also called Mitsubishi diagnostic code P4.
Homeowner? What Mitsubishi code P4 means for you
Check, then call Your heat pump is reporting: Drain float switch disconnected. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.
Safe things you can check yourself
- Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
- Check both breakers and the outdoor disconnect box beside the outdoor unit; all should be ON.
- Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
- In winter, keep snow and ice off and away from the outdoor unit. A short defrost cycle with steam is normal.
- Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does Mitsubishi error code P4 mean?
Pins 3 and 4 of the float switch connector CN4F are not closed, so the board thinks the float switch is unplugged. Checked all the time the unit runs. Some controllers show this as 5701.
Applies to: PEAD-RP35/50/60/71/100/125/140JA and JA(L) ducted indoor units (220-240 V models)
Common causes of Mitsubishi code P4
- Float switch connector CN4F loose or not plugged in
- Faulty indoor control board
Mitsubishi models that use code P4
PEAD-RP35JAPEAD-RP35JALPEAD-RP50JAPEAD-RP50JALPEAD-RP60JAPEAD-RP60JALPEAD-RP71JAPEAD-RP71JALPEAD-RP100JAPEAD-RP100JALPEAD-RP125JAPEAD-RP125JALPEAD-RP140JAPEAD-RP140JAL
Other Mitsubishi Heat Pump codes
All Mitsubishi Heat Pump error codes →
Mitsubishi code P4: homeowner questions
What does Mitsubishi code P4 mean?
Drain float switch disconnected. Pins 3 and 4 of the float switch connector CN4F are not closed, so the board thinks the float switch is unplugged. Checked all the time the unit runs. Some controllers show this as 5701.
Is it safe to keep using my heat pump with code P4?
It depends on the cause. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.
Can I reset Mitsubishi code P4 myself?
You can try one reset (power off for 30 seconds, then on). If Mitsubishi code P4 comes back, the cause is still there and a licensed technician should check it.
Who can fix Mitsubishi code P4 near me?
Aurora Star Tech Inc. repairs Mitsubishi heat pumps in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: AC Running But Not Cooling: What to Check · Heat Pump Not Heating or Blowing Cold Air
Troubleshooting guides
- Indoor board LED1 and LED2 both off - no power Mitsubishi · Heat Pump
- Indoor board LED2 blinking - remote controller line problem Mitsubishi · Heat Pump
- Indoor fan does not run Mitsubishi · Heat Pump
- PLEASE WAIT stays on, or an error shows about 2 minutes after power-up Mitsubishi · Heat Pump
Source: Mitsubishi Electric PEAD-RP35-140JA(L) Service Manual, 10-3 Self-diagnosis action table, p.31. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.