Lg Mini Split P4 Error Code

Updated 2026-08-29 · review status: manual-verified Last verified: 2026-08-29

Quick answer

P4 means an over-temperature protection event on LG models that display P-codes instead of CH codes: the unit is protecting itself from high outdoor temperature in cooling or high indoor temperature in heating. LG's own guide groups P4/P6/P7/P8 with CH34-style temperature protection, and points to poor air intake (dirty filter) and outdoor ventilation as the usual causes. Correct airflow, reset once; a returning code needs service.

Severity: medium · DIY difficulty: simple

Safety

Only a power-cycle reset and airflow/filter checks you can do without removing any panel. Do not open the outdoor unit, test inverter board voltages, connect gauges, or add refrigerant - high-voltage and refrigerant work is technician-only.

What P4 means

P4 means an over-temperature protection event on LG models that display P-codes instead of CH codes: the unit is protecting itself from high outdoor temperature in cooling or high indoor temperature in heating. LG's own guide groups P4/P6/P7/P8 with CH34-style temperature protection, and points to poor air intake (dirty filter) and outdoor ventilation as the usual causes. Correct airflow, reset once; a returning code needs service.

Code meaning varies by series

  • LG Mega R-32 / models that map P-codes to CH codes: Shown instead of CH 61 (or CH34-family over-temperature protection): high outdoor temperature in cooling or high indoor temperature in heating
  • Other LG lines (variant readings): Some LG model lines use P4 for other faults (for example a drain pump / water level sensor error on certain P/F/E series units); on Multi-V style outdoor displays P4 has been listed as compressor over-heat (thermistor).

Causes, ranked

  1. 1. Poor outdoor airflow - poor ventilation, hot exhaust recirculating, or objects blocking the condenser occasional diy-ok

    Check: With the unit off, clear leaves, snow, and debris around the outdoor unit; make sure hot discharge air is not recirculating into the intake (minimum clearances per the manual).

    Fix: Correct airflow, wash indoor filters, power cycle once; if the code returns, call a technician.

  2. 2. Clogged or dirty indoor filter / poor indoor air intake (heating mode) occasional diy-ok

    Check: Remove the user-accessible filter, wash, dry, and reinstall it firmly.

    Fix: Clean filters and reset once; repeated trips mean the protection is finding a real temperature problem.

  3. 3. Outdoor fan not moving enough air over the coil (failing fan motor) occasional pro-only

    Check: Technician only: confirm fan runs and RPM during operation.

    Fix: Technician: diagnose and replace the outdoor fan motor if required.

  4. 4. Refrigerant or compressor issue driving real over-temperature (low charge, restriction) occasional pro-only

    Check: Technician only: pressures, temperatures, and charge check (EPA 608 for refrigerant work).

    Fix: Technician: leak test, correct charge, or compressor diagnosis.

  5. 5. Temperature sensor/thermistor misreading occasional pro-only

    Check: Technician only: thermistor resistance against the chart.

    Fix: Technician: replace the out-of-spec sensor.

Related codes

lg/ch61 · lg/p7 · lg/p8 · lg/h34

Commonly searched as: "lg p4" · "lg error code p4" · "lg air conditioner p4"

Sources

  • SplitAtlas LG P4 page (LG: some models show P4 instead of CH 61 over-temperature protection) — verified 2026-08-29
  • LG official support - Guide to error codes (P4, P6, P7, P8 or CH34 depending on model; heating high-temperature protection from poor air intake) — verified 2026-08-29
  • Be Cool Air Conditioning - LG air conditioner error codes (P-series variant readings by model line) — verified 2026-08-29