If your LG refrigerator suddenly shows Er CO (sometimes shown as ErC0 or Er C0), it’s usually a communication problem between the refrigerator’s main control board and the display/control panel. In plain English: the brain of the fridge and the face you use to control it aren’t talking to each other properly. That can cause the display to blink, the settings to be unresponsive, or the fridge to stop certain functions until the error clears. This guide explains what the error is, why it happens, step-by-step checks you can do at home, and simple preventive tips to keep it from coming back.
What the Er CO error actually is
- Er CO = communication error between the display/control panel and the main control board.
- Symptoms include an unresponsive display, controls that don’t register, or the fridge refusing to run some cycles.
- The fault is typically electrical (wiring, connectors) or electronic (control board or display module).
Most common causes
The issue usually comes down to one of a few things: wiring or connector problem, a faulty display/control panel, or a failing main control board. Physical damage, moisture, or a mismatched replacement board are frequent culprits. Occasionally a temporary glitch (software hiccup) will trigger the error but clears after a power reset.
Quick checklist you can run now
- Unplug the fridge or switch its breaker off for about five minutes, then power it back on to see if the error clears.
- Inspect the wire harness that runs between the display and the main control board for loose plugs, pin damage, or signs of burning.
- Look for obvious signs of damage (burn marks, melted plastic) on the control board — especially the underside where heat concentrates.
- Confirm whether any recent repairs included replacing the control board; if so, check the replacement part number carefully — incompatible boards can cause Er CO.
Safety first — before you touch anything
Always disconnect power before accessing electrical components. Wait until any internal lights are off and the appliance is fully de-energized. Use insulated tools and bright lighting. If you’re uncomfortable with electrical work, stop and call a trained appliance technician. Safety beats saving a few dollars.
Step-by-step DIY diagnosis
Start simple and only proceed if you’re comfortable.
- Power cycle the fridge. Unplug it or turn off the breaker for five minutes, then plug it back in. Sometimes a temporary communication fault will clear.
- Remove the control panel/display cover (follow your model’s manual instructions). Look for a ribbon cable or harness that connects the display to the main board. Ensure connectors are fully seated.
- Check the wiring harness visually along its length: look for pinched sections, melted insulation, or kinks. Gently wiggle connectors while watching the display to test for intermittent behavior.
- Access the main control board (usually behind the bottom kickplate or inside the back panel). Inspect both sides for burnt spots, bulging capacitors, cracked solder joints, or discoloration. Pay special attention to the underside and connector pins.
- If you have a multimeter and know how to use it safely, verify continuity across the harness and test for obvious shorts. Don’t attempt live testing unless you’re trained and the fridge is safely powered for that test.
When to replace parts — and which ones
If the display cable is damaged or a connector is corroded, replacing or repairing the harness often fixes Er CO. If the display module itself fails (unresponsive buttons, blank or frozen display despite good wiring), replace the display panel. If the board shows burn marks, smells of burnt electronics, or components are visibly damaged, replace the main control board.
- If replacing the control board, match the OEM part number exactly. Using a look-alike or incorrect revision can create communication mismatches and make the error worse.
- Replacing the display module is usually straightforward: unplug connectors, swap the module, and reattach. Keep fasteners and ribbon cables secure.
When a simple swap won’t fix it
If you replaced the control board recently and Er CO appeared afterwards, there’s a chance the replacement board isn’t compatible. Double-check the part numbers and model revisions. Also consider whether other components (like an inverter or separate display controller) are involved — some LG designs use multiple boards that must match the firmware revision.
Preventive tips to avoid Er CO in the future
- Keep the area behind and under the fridge clean and dry to prevent heat buildup and moisture damage to electronics.
- Avoid pushing/pulling the fridge roughly — strain on harnesses can loosen connectors or damage wiring.
- When servicing, always route wiring as routed by the factory and secure loose harnesses with clips or ties.
- Use surge protection on the circuit feeding the refrigerator; power spikes and brownouts can damage control electronics.
- If you must replace boards, use OEM parts or verified compatible modules and record model/part numbers for future reference.
How to decide whether to DIY or call a pro
Simple checks (power cycle, reconnecting harnesses) are safe for most handy homeowners. Visual inspections and part swaps are reasonable if you’re comfortable removing panels and handling electronics with power off. If you find burn marks on a control board, the board smells burnt, or you lack the correct replacement part number, calling a qualified technician is the smarter, safer choice.
Final summary — fast action plan
- Try a five-minute power reset first.
- Inspect and reseat connectors between the display and main board.
- Look for burned components or damaged wiring; replace the affected part.
- If you replace the board, make sure the replacement is the correct OEM model.
- Use surge protection and secure wiring to reduce the chance of recurrence.