- Appliances
- Refrigerators
Er CO
LG Er CO on a refrigerator: no communication between main board and display
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
LG says CO appears when the main board and the display board cannot communicate. Unplug the fridge or switch off its breaker, wait about 5 minutes and use it again. If CO repeats, LG asks for a technician to check it.
Safety first
Stop and check this first
- The main board is connected to mains voltage: do not open its cover or touch the wiring. The boards and their connections are the LG technician's job.
Safe checks you can perform
- 5 minute reset
- Food temperature
- When CO appears
Leave these tasks to a qualified professional
- Do not attempt this professional task: Wiring and board check
- Do not attempt this professional task: Test after the repair
What a technician must be able to justify
A technician is coming
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Wiring and board check
What they doThe LG technician unplugs the fridge and checks the wire between the main board and the display before judging the boards.
They must show youthe connector and wire checked.
In writingthe cause and the reference of any replaced board, with the reason.
Test after the repair
What they doAfter the repair, the fridge is started and the technician confirms the display responds and CO does not return.
They must show youthe display working without the code.
In writingthe test result.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Checks and evidence, step by step
Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
- 1
5 minute reset
No special tools
Procedure
- Who:
- you.
- How:
- unplug the fridge or switch off its dedicated breaker, wait about 5 minutes and restore power, as LG instructs.
- Result that matters:
- CO does not return.
- If it does not return:
- it was a one-off power disturbance; note the date.
- If it returns:
- LG asks for a technician to check it; do not keep resetting.
- Evidence to keep:
- a photo of the code and the date of the reset.
Evidence: LG Refrigerator - Troubleshooting an E CO Error Code
- 2
Food temperature
No special tools
Procedure
- Who:
- you.
- How:
- put an appliance thermometer in the fridge and another in the freezer, and keep the doors closed while you see whether the fridge keeps cooling with the code on the display.
- Result that matters:
- the CDC sets 40 °F (about 4 °C) or below in the fridge and 0 °F (about -18 °C) or below in the freezer.
- If the readings are within range:
- the food is still protected; check the thermometers again every few hours.
- If the fridge is above 40 °F:
- with the door closed, the CDC gives the fridge 4 hours at most and a full freezer 48 hours (24 if half full). Frozen food that still has ice crystals or is at 40 °F or below can be refrozen. When in doubt, throw it out without tasting it.
- Evidence to keep:
- a photo of each thermometer with the time and a list of what you threw away.
Evidence: Keep Food Safe After a Disaster or Emergency
- 3
When CO appears
No special tools
Procedure
- Who:
- you.
- How:
- note whether CO appears after power cuts, storms or when opening and closing the doors.
- Result that matters:
- giving the technician clues about power or wiring, the causes LG lists.
- If it matches cuts or storms:
- unstable power becomes more likely.
- If it appears with no link to the power:
- wiring or a board becomes more likely.
- Evidence to keep:
- a list of dates and circumstances.
Evidence: LG Refrigerator - Troubleshooting an E CO Error Code
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Appliances
- Brand
- LG
- Product type
- Refrigerators
Known code variants
- CO
- CO frigorífico LG
- E CO
- ER CO
- Er(E) CO
- Error CO LG
- LG CO error
- LG refrigerator CO
What it means
LG explains that CO appears when there is no communication between the main board and the display board. It lists temporary unstable power, a main board or display board failure, and a disconnected wire as possible causes. Its home step is a reset: unplug or switch off the breaker and use it again after about 5 minutes. If the same code repeats, LG says an LG technician should check it. The code does not say which board or which wire fails.
Warnings and stop conditions
- Mediumeditorial warning
The main board is connected to mains voltage: do not open its cover or touch the wiring. The boards and their connections are the LG technician's job.
Evidence: LG Refrigerator - Troubleshooting an E CO Error Code · How to Troubleshoot the Error Codes on Your LG Refrigerator
Symptoms and causes
Probable causes · in order
- Temporary unstable powerPossible
LG lists it as a possible cause. It fits if CO clears with the 5 minute reset and does not return.
Evidence: LG Refrigerator - Troubleshooting an E CO Error Code
- Disconnected wire between boardsPossible
LG includes it among the causes. It can only be told apart from a board failure by the technician's check, with the fridge unplugged.
Evidence: LG Refrigerator - Troubleshooting an E CO Error Code
- Main board or display board failurePossible
If CO repeats after the reset, LG refers you to its technician; replacing a board should be backed by checking the wiring first.
Evidence: [LG Refrigerator] Digital and Analog Error Codes · LG Refrigerator - Troubleshooting an E CO Error Code
Virtual technician
Does Er CO still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
[LG Refrigerator] Digital and Analog Error Codes
LG Electronics · 2025 · official_doc
- 2
LG Refrigerator - Troubleshooting an E CO Error Code
LG Electronics · 2023 · official_doc
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