LG Refrigerator Error Code I/M-Sensor Error

The I/M-Sensor Error means the refrigerator's main control board has detected an abnormal signal from the temperature sensor located in the ice maker. The board monitors voltage at connector CN90 between pins 8 and 4, expecting a reading between 1.0V and 4.5V. When the signal falls outside that range, the error code is triggered. This can point to a failed sensor, a wiring problem, or a connector issue.

This error does not typically present a safety hazard to you or your home. It primarily affects ice maker operation and can prevent proper ice production. Food stored in the main refrigerator and freezer compartments is not usually at risk, but you should monitor temperatures to confirm the freezer is maintaining safe levels while the issue is present.

A reset may temporarily clear the error code from the display, but if the underlying fault in the sensor, wiring, or connector has not been corrected, the error will return. Resetting the unit without diagnosing the root cause is not a long-term solution. Use the reset as a way to confirm whether the error comes back after a repair, rather than as the repair itself.

Some causes of this error are DIY-friendly. You can start by inspecting the wiring harness running from the ice maker to the main PCB for visible damage, and by reseating the connector at CN90. If you have a multimeter, checking the voltage at CN90 pins 8 and 4 will help confirm whether the sensor or board is at fault. Sensor replacement is a moderate-difficulty repair, while main PCB replacement is more involved and may benefit from a professional technician.

Repair costs vary depending on the root cause. A replacement ice maker temperature sensor typically costs between 15 and 50 dollars for the part alone. A main PCB replacement is significantly more expensive, ranging from 150 to 400 dollars or more for the part. Adding professional labor, total repair costs can range from around 100 dollars for a simple sensor or connector fix to 400 dollars or higher if the main board needs replacement.