LG mini split error code CH25
Abnormal input voltage (over or under). Also shown as CH 25, CH25.
- TypeProtection
- SystemPower supply
- Can I fix it?Homeowner checks, then maybe a tech
What CH25 means on a LG
Supply voltage went outside the safe window.
On this platform, CH25 is a protection: the system stopped or throttled itself to prevent damage; many clear on their own once conditions return to normal.
Common causes
- Utility voltage sag or spike.
- A loose connection or a lost leg on a 230 V circuit.
- An undersized generator.
How to fix it yourself
Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician.
- Reset the system: switch the breaker (or the outdoor disconnect) off, wait a full five minutes so the boards fully discharge, then switch it back on and restart from the remote.
- If you own a multimeter and are comfortable using it, measure the supply voltage at the outdoor unit's L1 and L2 terminals with the unit running. A 230 V system should read roughly 208 to 253 VAC.
- With power off, tighten every power connection.
Switch off power at the breaker before opening either unit. Capacitors in the outdoor unit hold a charge for several minutes after power is cut.
When to call a technician
Normal voltage with a persistent CH25 means the outdoor board.
Which LG units show CH25
This page applies to LG Art Cool, Standard, Mega and Multi F units. LG's own documentation lists CH25 as "Abnormal input voltage (over or under)", the same definition used across the LG it is built on. If your unit shows a code with a different shape (for example a four-character code, or a plain number), it is from a different table; use the lookup with your exact code.
Where LG shows this code
The indoor display shows CH followed by a number (CH05, CH38). Units without a display blink the indicator lamps in a pattern; the outdoor board LEDs blink the same number. If someone tells you 'CH 5', that is CH05. CH01 to CH12 are indoor-unit faults, CH21 to CH29 are inverter and compressor faults, CH32 to CH38 are refrigerant-side protections, CH40 to CH48 are outdoor sensors, and CH51 to CH73 are outdoor-unit system faults.
Other LG codes
Same part of the system as CH25:
Questions people ask
Can I reset a LG CH25 code myself?
Yes. Turn the system off at the breaker for five minutes, then restart it. If CH25 comes back, the fault is real and needs the checks above.
Is it safe to keep running a LG showing CH25?
Not repeatedly. A protection code means the unit stopped itself to prevent damage, and resetting it over and over can turn a cheap repair into a compressor failure. Reset once, check the basics, and stop if it returns.
Do I need a technician for LG CH25?
Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician. Normal voltage with a persistent CH25 means the outdoor board.
Sources
- LG residential split service manuals (error code tables)
Updated September 2026. Codes and definitions vary by model year. If your manual disagrees with this page, your manual wins. Send a correction.