LG Mini Split P4 Error Code

Updated 2026-08-30 · review status: manual-verified · reviewed by MiniSplitDecoder Editorial Team Last verified: 2026-08-30

Check your model first

  • LG Mega R-32 wall-mounted series and other LG models that show P-codes instead of CH codes
  • LG Mega R-32 / models that map P-codes to CH codes
  • Other LG lines (variant readings)

Match the model on your equipment label to the linked manufacturer documentation. The same code can mean different things across model families.

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: easy

Safety

Stop at the breaker power-cycle and any plug-accessible checks (filters, remote settings, visible wiring). The outdoor unit's capacitor holds a lethal charge and the refrigerant circuit is both pressurized and (on R-32 units) flammable — opening panels or servicing the sealed system is licensed-technician work (EPA 608).

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).

First checks before service

This page currently documents the safe reset triage. If the code returns, use the linked source manual or a qualified technician for code-specific diagnosis.

  1. 1. One-time fault event (power disturbance or transient sensor reading) common DIY

    Check: Power-cycle at the breaker/disconnect (or unplug for CPAP), restore, and run the system while watching for the code.

    Fix: If the code does not return after a full run cycle, the fault was transient — monitor, no repair needed.

  2. 2. Fault persists after a clean reset occasional pro only

    Check: If the code returns immediately or every session, note the conditions (startup, heating, after rain).

    Fix: A persisting code points at the component the manual assigns to this code — that repair is technician territory.

Related codes

Cross-references for the same fault family, by brand:

LG P7 · LG P8 · LG H34

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

Sources

Related Mini Split guides

Mini-Split Communication Error: DIY Checks · Mini-Split Flashing Light Decoder: Blink Patterns · Mini-Split Leaking Water Inside? The Clogged Drain Fix · Mini-Split Maintenance Checklist: Seasonal DIY Tasks