While the error code itself is the most obvious sign, you may also notice that your refrigerator is over-cooling or under-cooling, as it can no longer compensate for the warmth of your kitchen. You might hear the fans running at unusual intervals, or notice the ice maker performing poorly. Rest assured, while this sounds technical, it is a very common issue that can typically be resolved with basic tools and a bit of patience.
| Category | Specification |
|---|---|
| Difficulty Level | Moderate (Requires basic electrical testing) |
| Estimated Time | 45 – 75 Minutes |
| Tools Needed | Phillips Head Screwdriver, Digital Multimeter, Small Flathead/Putty Knife |
| Estimated Cost | $20 – $60 (Depending on part source) |
Symptoms of Error Er rt
The most immediate symptom is the digital display on the door or inside the cabinet flashing “Er” in the refrigerator temperature section and “rt” in the freezer section. However, the physical manifestations can be more subtle before the code becomes permanent. You may notice that the refrigerator seems to ignore the ambient heat of a hot summer day, failing to ramp up the compressor, or conversely, it may run constantly even when the room is cool.
⚡ Warning: Check Manual First
Before unscrewing any panel, ensure you have the correct service manual for safety.
In some French Door models, this error can lead to erratic behavior in the “Linear Compressor” logic, causing the unit to enter a “limp mode” where it maintains a baseline cooling level that isn’t quite cold enough for food safety. You might also notice lukewarm water from the dispenser or frost buildup on the evaporator coils if the control board defaults to a generic defrost timer rather than a temperature-dependent one.
Why is my LG showing Error Er rt?
The “Er rt” error is rarely a “glitch” and usually points to a hardware failure within the ambient sensing circuit. Here are the primary reasons why this circuit fails:
- Thermistor Degradation: The ambient sensor is a Negative Temperature Coefficient (NTC) thermistor. Over time, the internal chemical composition of the resistor can break down due to humidity and temperature fluctuations. This causes its resistance to drift out of the range expected by the control board, triggering the error.
- Wiring Harness Corrosion: On many LG French Door models, the ambient sensor is located on the top hinge cover or near the control board housing. Because this area is exposed to kitchen humidity (especially from stovetop steam), the pin connectors can develop micro-corrosion, which increases resistance and interrupts the low-voltage signal.
- Voltage Spikes: The main PCB (Power Control Board) is sensitive to power surges. A spike can damage the specific “input” port on the microprocessor that reads the ambient sensor. In this case, even a new sensor won’t fix the problem; the board itself would need replacement.
- Physical Vibration: Refrigerator compressors create constant micro-vibrations. Over years of operation, these vibrations can wiggle the sensor’s harness plug loose from the main control board, resulting in an “open circuit” error.
Troubleshooting & Replacement Instructions
- Safety First: Complete Power Disconnection
Before touching any electrical components, unplug the refrigerator from the wall outlet. If the plug is inaccessible, shut off the dedicated circuit breaker in your home’s electrical panel. WARNING: Control boards contain large capacitors that can hold a charge even after power is removed. Wait at least 5 minutes after unplugging before proceeding to allow these components to discharge safely.
- Accessing the Main Control Board
The ambient sensor usually connects directly to the Main PCB. On most LG French Door models, this board is located on the top of the refrigerator under a metal or plastic cover. Use your Phillips head screwdriver to remove the screws securing the panel. Carefully lift the panel; be mindful that some panels have sharp edges. Set the screws aside in a safe place so they don’t roll behind the appliance.
- Locating the Ambient Sensor
The ambient sensor itself is a small, plastic-encased bulb, often tucked into a small grille on the top hinge cover or clipped near the PCB housing. Trace the wires from this sensor back to the control board. It is typically a two-wire connector. Look for any obvious signs of pinched wires or black “burn” marks on the connector.
- Performing a Multimeter Continuity and Resistance Test
Set your digital multimeter to the Ohms (Ω) setting. Disconnect the sensor plug from the board. Place your probes on the two pins of the sensor’s plug. At a standard room temperature of 77°F (25°C), the sensor should read approximately 10,000 Ohms (10kΩ). If the meter shows “OL” (Open Loop) or “0.00” (Short Circuit), the sensor is definitely faulty and must be replaced.
- Installing the New Sensor
If the test fails, purchase a genuine LG ambient thermistor. Simply unclip the old sensor from its mounting bracket and plug the new harness into the control board. Ensure you hear a distinct “click” when plugging it in to confirm a secure connection. If the sensor was located inside a plastic grille, ensure it is seated properly so it can accurately measure the room air rather than the heat generated by the PCB itself.
- Reassembly and System Reset
Replace the PCB cover and secure it with the screws. Plug the refrigerator back into the power source. The error code should vanish immediately. In some cases, you may need to “reset” the display by holding the “Fridge” and “Freezer” buttons (or “Ice Plus” and “Freezer”) simultaneously for 5 seconds until the display beeps.
How to Prevent Error Er rt
Preventing sensor failure is largely about protecting the refrigerator’s sensitive electronics from environmental stressors. While you cannot stop a component from aging, you can certainly extend its lifespan.
- Install a High-Quality Surge Protector: Since the Er rt error can be caused by damaged logic gates on the control board, a dedicated appliance surge protector is vital. LG’s linear compressors and PCB assemblies are particularly sensitive to “dirty” power and brownouts.
- Control Kitchen Humidity: Excessive steam from cooking can settle on the top of the refrigerator, where the ambient sensor and control board reside. Use your range hood’s exhaust fan consistently to pull moisture away from the appliance.
- Clear the Top of the Refrigerator: Many people use the top of the fridge for storage (cereal boxes, trays). This can trap heat around the ambient sensor and control board, causing the sensor to operate at higher-than-normal temperatures, which accelerates the degradation of the NTC material.
FAQ
Frequently Asked Questions
Can I still use my refrigerator while the Er rt code is active?
Yes, the refrigerator will usually continue to cool, but it will do so inefficiently. It may run longer than necessary, increasing your electricity bill, or it may fail to maintain a consistent temperature during the day. It is best to fix it within a few days to avoid food spoilage or excessive wear on the compressor.
I replaced the sensor, but the Er rt error is still there. What now?
If a new sensor doesn’t clear the code, the issue likely lies within the Main PCB (Control Board). The circuit on the board that interprets the sensor’s resistance has likely failed. You will need to replace the entire control board, ensuring the part number matches your specific model’s serial number.
Where is the “Room Temperature” sensor actually located?
On most LG French Door models, look at the very top of the unit. There is often a plastic cover over the door hinges. The sensor is frequently hidden inside a small ventilated slot on the left or right hinge cover, or it is mounted directly to the plastic housing of the control board on top of the cabinet.