LG dishwasher UO error code
LG Dishwasher UO Error Code: Troubleshooting & Repair Guide
If you are seeing an LG dishwasher UO error code on your display, you might be confused because this specific code is technically associated with Frigidaire or Electrolux models, where it indicates a “Vent Open” failure. However, if you are searching for the LG dishwasher UO error code, you are likely experiencing one of two things: a misinterpretation of the “OE” (Drain Error) code, or a specific failure in your dishwasher’s drying assembly that mimics the “UO” behavior found in other brands.
This guide will help you decipher the code and troubleshoot the specific components—such as the vent motor and wax motor—that are often the root cause of these symptoms in appliance repair.
What Does the LG Dishwasher UO Error Code Mean?
On most standard LG dishwashers, a true “UO” code does not exist in the official manual. It is highly probable that you are seeing OE (Drain Error) and reading it incorrectly due to a digital display segment failure or viewing angle.
- OE Error: Indicates a drainage issue (clogged pump, hose, or drain).
- “Phantom” UO Error: If you are certain the code is UO, or if your dishwasher is failing to dry dishes properly (leaving them soaking wet), you should treat this as a Vent/Drying Assembly failure.
Since the “UO” code in the appliance industry specifically points to the vent assembly, we will focus on troubleshooting the vent motor, wax motor, and fan motor, which are the components responsible for venting steam and drying your dishes.
Troubleshooting the Vent and Drying Assembly
If your LG dishwasher completes a cycle but the dishes are wet, or if you suspect the vent system is triggering a fault, the problem lies within the drying assembly. This system uses a vent motor to circulate air and a wax motor to open and close the vent seal.
1. Inspecting the Wax Motor
The wax motor is a small actuator that pushes a plunger to open the vent door during the drying cycle. If this component fails, the vent remains closed, trapping moisture inside.
- Location: Inside the door panel, usually near the detergent dispenser or the top venting duct.
- Failure Symptom: The vent does not open, and dishes remain hot and wet.
2. Checking the Vent Fan Motor
The fan motor actively pulls moist air out of the tub. A seized or burnt-out motor will prevent the steam vent from functioning.
- Location: Mounted to the drying assembly inside the door.
- Failure Symptom: You do not hear the soft hum of the fan during the drying stage (usually the last 30-45 minutes of the cycle).
Step-by-Step Diagnostic & Repair
To accurately diagnose the issue, you will need a multimeter and basic tools like a screwdriver. Follow these steps to test the components.
Step 1: Enter Diagnostic Mode
Before taking the machine apart, try to run a system test.
- Turn the dishwasher off.
- Press the Power and Start buttons simultaneously (or Power and Rinse) depending on your model.
- This enters Diagnostic mode. Press the Start button repeatedly to cycle through components.
- Listen for the fan motor to engage. If it tries to spin but sounds grinding or is silent, the motor is likely defective.
Step 2: Access the Control Board and Wiring
If the motor doesn’t run, the issue could be the control board or the wiring harness.
- Safety First: Unplug the dishwasher or flip the breaker.
- Remove the screws on the inner door panel to separate the outer door skin.
- Inspect the wiring harness running from the bottom of the door to the control board. Look for pinched or broken wires, particularly at the door hinge where flexing occurs.
- Check the board for any burn marks or loose connectors.
Step 3: Multimeter Testing (Continuity Test)
If the wiring looks good, you must perform a continuity test on the motors.
- Set your multimeter: Turn the dial to the Ohms/Resistance setting (Ω).
- Test the Vent Motor: Disconnect the wire connector from the fan motor. Place the probes on the motor terminals.
- Reading: You should see a resistance value (typically between 50Ω and 200Ω). If the meter reads “OL” (Open Loop) or infinite resistance, the motor is dead and needs replacement.
- Test the Wax Motor: Similarly, place probes on the wax motor terminals.
- Reading: A functional wax motor typically reads between 1kΩ and 3kΩ. If it reads open (OL), the wax has failed to expand, and the drying assembly will not open.
Step 4: Moisture Sensor Check
Some premium LG models use a moisture sensor to adjust drying time. If this sensor is coated in hard water buildup or debris, it may send false signals to the control board, preventing the vent cycle from starting. Cleaning this sensor with vinegar can sometimes resolve drying issues.
Summary
While the LG dishwasher UO error code is often a case of mistaken identity for the “OE” drain error, treating it as a ventilation fault is the best course of action if your dishes are not drying. By testing the vent motor and wax motor with a multimeter, you can isolate the faulty part and restore your appliance’s performance without calling for professional service.
Frequently Asked Questions
Does the LG dishwasher actually have a UO error code?
No, a “UO” code is not listed in official LG dishwasher manuals. It is usually a misinterpretation of the OE error code (Drain Error) caused by a faulty digital display segment. However, since “UO” refers to a vent failure in other brands, it is often used as a shorthand for LG drying assembly malfunctions where dishes remain soaking wet.
How can I tell if my issue is a drainage problem or a drying problem?
If the dishwasher stops mid-cycle and has standing water at the bottom of the tub, you are dealing with an OE drain error. If the cycle finishes completely but the dishes are hot and wet, the problem is likely a failure in the vent motor or wax motor within the drying assembly.
What is the role of the wax motor in an LG dishwasher?
The wax motor acts as an actuator that opens the vent seal during the drying phase. When it receives power, the wax inside expands and pushes a plunger to open the vent door, allowing steam to escape. If this component fails, the vent remains closed and moisture stays trapped on your dishes.
How do I test the vent components with a multimeter?
To test the vent or fan motor, set your multimeter to the Ohms (Ω) setting and touch the probes to the component terminals. A functional fan motor should show a resistance between 50Ω and 200Ω, while a wax motor should read between 1kΩ and 3kΩ. A reading of “OL” (Open Loop) indicates the part is dead and requires replacement.
Can a dirty sensor cause drying failures?
Yes. Some premium LG models feature a moisture sensor that tells the control board when to end the cycle or open the vent. If this sensor is covered in mineral deposits or hard water buildup, it can send incorrect data. Cleaning the sensor with a soft cloth and vinegar can sometimes fix “phantom” drying issues without replacing any parts.