LG Refrigerator Error Code E CO

E CO indicates a communication error between the main PCB's Micom and the display board's Micom. The two control boards have lost their data link, which can be caused by a loose wiring connection or a failed transistor in the Tx/Rx circuitry on either board. The first diagnostic step is to check for loose connectors and then verify that 12V is present at pins 5 and 6 of connector CON101 on the main board.

A communication failure between the main board and display board can prevent the refrigerator from responding correctly to temperature commands or displaying accurate readings. Food safety may be at risk if the cooling system is not operating normally. It is best to verify that the refrigerator is actually maintaining proper temperatures and address the error promptly rather than continuing to use it in a degraded state.

Repair costs vary depending on the root cause. If only connector reseating is needed, the fix may cost nothing beyond a service call fee, which typically ranges from $75 to $150. If a display board replacement is required, parts and labor can range from $150 to $350 or more. Main PCB replacement tends to be the most expensive option, often falling in the $200 to $450 range depending on the model and labor rates in your area.

Reseating loose harness connectors is a straightforward task most homeowners can handle safely with the refrigerator unplugged. However, diagnosing a failed Tx/Rx transistor or a faulty PCB requires a multimeter, familiarity with reading circuit boards, and the ability to safely work with appliance electronics. If basic connector checks do not clear the error, a qualified technician should perform the component-level diagnosis.

A power reset, performed by unplugging the refrigerator for a few minutes and plugging it back in, may temporarily clear the error if it was triggered by a transient communication glitch. However, if the underlying cause is a loose connector, low voltage at CON101, or a failed transistor, the error will return. A reset is a reasonable first step but is not a substitute for proper diagnosis.