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Mitsubishi P5: drain pump error (P-Series PKA-A and PLA-A)

By How House Works EditorialBased on Mitsubishi Electric manualsChecked against sources Updated

Mitsubishi Electric display

P5

“Drain pump error”

PKA-A KA8, PKA-A LA1, PLA-A EA8 · TCH115A (PKA-A KA8) p. 12; TCH115A (PKA-A KA8) p. 14; TCH117 (PKA-A LA1) p. 12; TCH117 (PKA-A LA1) p. 14; TCH120A (PLA-A EA8) p. 16; TCH120A (PLA-A EA8) p. 19
Technician

Self-check: 5 beeps and blinks, shared with PA. Action table: drain overflow protection; the float switch detected underwater for 1 minute 30 seconds with the drain pump on turns off the compressor and the indoor fan. The PLA-A EA8 manual adds drain pump lock protection (PLA-A EA8 Service Manual TCH120A, p. 19).

What it means

P5 is a check code of Mitsubishi’s P-Series PKA-A and PLA-A EA8 indoor units, and the code table calls it “Drain pump error”. A wired controller shows “P5”. In self-check with a wireless remote it is 5 beeps and 5 blinks, the same count as PA PKA-A24/30/36KA8 Service Manual TCH115A, p. 12; PKA-A12/18LA1 Service Manual TCH117, p. 12; PLA-A EA8 Service Manual TCH120A, p. 16.

The action table describes drain overflow protection. If the drain float switch is underwater for 1 minute 30 seconds in a row while the drain pump is on, the unit records a suspensive abnormality and turns off the compressor and the indoor fan. If the same condition is detected again during that state, the drain pump is judged abnormal PKA-A24/30/36KA8 Service Manual TCH115A, p. 14; PKA-A12/18LA1 Service Manual TCH117, p. 14; PLA-A EA8 Service Manual TCH120A, p. 19.

The PLA-A EA8 manual adds a second trigger, drain pump lock protection: if the pump stops for 5 seconds in a row while it should be running, the error is postponed, and if that repeats 4 times the pump is judged abnormal PLA-A EA8 Service Manual TCH120A, p. 19.

Causes listed: a drain pump that malfunctions, a clogged drain pump or drain pipe, a float switch that is caught or has moving parts that stick so it reads as underwater, and a defective indoor controller board PKA-A24/30/36KA8 Service Manual TCH115A, p. 14.

PA shares the 5-blink count but is a separate code, “Forced compressor stop (due to water leakage abnormality)”. The technician’s action table says that once PA is detected, the abnormality is not released until the main power is reset PKA-A24/30/36KA8 Service Manual TCH115A, p. 16. This page gives no owner step for resetting power: we have no PKA-A or PLA-A owner’s manual, and the M-Series owner’s manuals forbid switching the breaker while the unit runs MSZ-GL Operating Instructions, p. En-1.

On M-Series MSZ wall units, 5 blinks of the indoor lamp means “Outdoor power system”, not a drain fault MSZ-GL Indoor Service Manual OBH732D, p. 27. The P-Series code table does not apply to them.

Check these first

The owner’s manuals for PKA-A and PLA-A units are not among our sources, so this page has no owner steps for the drain itself. If your wired controller is a PAR-40MAAU, its instruction book gives these:

  1. When an error occurs, the controller shows an error screen and its operation LED blinks. Check the error status, stop the operation and consult your dealer PAR-40MAAU Instruction Book, p. 65.
  2. If the code shows on the main display while the indoor unit keeps running, check the code and consult your dealer PAR-40MAAU Instruction Book, p. 9.
  3. F4 or the ON/OFF button resets the error that is occurring, unless ON/OFF operation is prohibited PAR-40MAAU Instruction Book, p. 66. The book does not say a reset fixes the cause.

When to call a licensed technician

  • The action table has the technician “Check if drain-up machine works”, check that the drain functions, test the drain float switch, and replace the float switch or the indoor controller board as the result shows PKA-A24/30/36KA8 Service Manual TCH115A, p. 14.
  • On PLA-A EA8 units, the lock-protection checks cover the drain pump, its connector and the pump circuit with the unit powered PLA-A EA8 Service Manual TCH120A, p. 19. This is technician work.
  • The table says it is not abnormal if none of the listed checks finds a problem, and that the power is turned off and on again to restart the unit after the check PKA-A24/30/36KA8 Service Manual TCH115A, p. 14.
  • The warning box on this page is quoted from an M-Series owner’s manual.

Notes for different models

  • PKA-A24/30/36KA8 and PKA-A12/18LA1 print the overflow trigger only. PLA-A EA8 prints both the overflow and the pump lock triggers under P5 PLA-A EA8 Service Manual TCH120A, p. 19.
  • P4 on the same units is a different drain fault: a contact failure of the float switch connector CN4F PKA-A24/30/36KA8 Service Manual TCH115A, p. 14.

Related Mitsubishi Electric codes

  • PA “Forced compressor stop(due to water leakage abnormality)”
  • P4 “Drain sensor error/Float switch connector (CN4F) open”

See also

Other ductless mini-splits: Daikin, Fujitsu, MrCool

All Mitsubishi Electric codes

Mitsubishi Electric is a trademark of its owner. How House Works is not affiliated with or endorsed by Mitsubishi Electric.

Sources

  1. Mitsubishi Electric Corporation. MSZ-GL Indoor Service Manual OBH732D. No. OBH732, Revised Edition-D, issued Feb. 2022; covers MSZ-GL06–24NA and MSY-GL09–24NA. Accessed Oct 12, 2026.
  2. Mitsubishi Electric. MSZ-GL Operating Instructions. Printed code DG79A01LH01 (the file name says JG79Y190H02); no publication date printed; covers MSZ-GL06/09/12/15NA and MSY-GL09/12/15NA; English pages are numbered En-1 onward. Accessed Oct 12, 2026.
  3. Mitsubishi Electric. PAR-40MAAU Instruction Book. Printed code WT09033X01; MA remote controller for CITY MULTI, M-series and P-series air conditioners. Accessed Oct 12, 2026.
  4. Mitsubishi Electric Corporation. PKA-A24/30/36KA8 Service Manual TCH115A. No. TCH115, Revised Edition-A, August 2023. Accessed Oct 12, 2026.
  5. Mitsubishi Electric Corporation. PKA-A12/18LA1 Service Manual TCH117. No. TCH117, March 2023. Accessed Oct 12, 2026.
  6. Mitsubishi Electric Corporation. PLA-A EA8 Service Manual TCH120A. No. TCH120, Revised Edition-A, August 2023; covers PLA-A12/18/24/30/36/42/48EA8. Accessed Oct 12, 2026.