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How To Get Rid Of Frigidaire Dishwasher UO Error Code?


The UO error code appears similarly in all Frigidaire dishwasher models. The wash tank filling process begins, followed by 3–4 clicks. The unit will drain water if you hit Cancel. However, the issue will recur with the next power-up. In this article, Jacob Dillard, an engineer at Appliance Repair Expert, will explain the main causes of this error and how to fix it.

Why Does The UO Error Code Appear?

According to the Frigidaire dishwasher manual, this fault code indicates a failure of the ventilation subunit or mainboard. The manufacturer recommends replacing them with new ones without inspecting and repairing them. On the other hand, some users come up with more cost-effective remedies after discovering the main reasons for the problem.

fridge cleaning
fridge cleaning
Frigidaire Dishwasher Error UO: Vent Assembly and Wiring Problem

Reason #1. Malfunctioning wiring

The fan has a wiring harness that extends through the bottom of the door to the control module. Using a multimeter, check their integrity. Ensure the electrical connections don’t become corroded when they get wet. It prevents the signal from passing through. The system does not receive a notification that the vent is closed. As a result, the error code UO is displayed.

fridge cleaning
fridge cleaning
Fan on the top of Frigidaire dishwasher

With a wire brush, clean the rusty contacts and add dielectric oil. Tighten up any loose joints. If the harness cannot be repaired, it should be replaced.

Reason #2. Problem with a valve or sensor

  1. Attempt to remove limescale and soap residue from the ventilation parts before discarding them.
  2. Remove the fastening ring by unscrewing it. Flip the vent and fan assembly over.
  3. To remove the lid, unscrew the two tiny screws. You’ll be able to see the rubber valve, which is controlled by a little solenoid.
  4. Unplug it and thoroughly clean it. Be careful: the optical sensor is controlled by a delicate plastic tab; do not break it!
  5. Perform these steps in reverse order to assemble the ventilation component.

Sometimes, it isn’t enough, and Frigidaire dishwasher error codes reappear. In this situation, clean the little optical sensor that informs the board of the plunger’s location. On a flat plate at the rear of the valve, the sensor element, labelled U1, is situated. Plaque may be removed using a nylon brush and lens solution.

Optical sensor
Optical sensor

Reason #3. Faulty ventilation subsystem

According to the manufacturer, this dishwasher component cannot be examined or fixed since the mechanism has been designed to be maintenance-free. In this case, it is simply recommended to replace the ventilation component. Furthermore, there are no assurances that such a solution will work since the next option for replacement – a control board – may also be defective.

Frigidaire Vent Assembly
Frigidaire Vent Assembly Replacement

Some people have figured out how to circumvent the “prohibition” on their own. It works if the optical sensor fails to accurately identify the position of the slider, resulting in the error code UO. To see whether it’s true, you’ll need to do the following:

  1. Ensure that the ventilation hole shuts properly at the start of the cycle;
  2. Remove the U1 element from the circuit board behind the valve to access the assembly.
  3. Replace the sensor with a new one.
fridge cleaning
fridge cleaning
Wax, fan and sensor

However, the engine might be an issue. The plunger will not shut the slider if the wax motor breaks, and the error UO disappears. This component is not repairable; you must replace the subunit completely.

Reason #4. Control module is broken

Frigidaire recommends replacing this component next. To get to it, loosen the front of the dishwasher’s screws, then remove the front panel and the waterproof covering. Check for corrosion and damage on the mainboard.

Frigidaire Dishwasher Control Board
Frigidaire Control Board

The UO error code for Frigidaire dishwashers indicates a faulty ventilation assembly and wiring, or in rare cases, the main control board. Troubleshooting should begin with checking the wiring harness, purge valve sensor, and ventilation assembly components. This will often resolve the UO error and avoid the need to replace parts. 

UO error codes can usually be resolved by carefully diagnosing and cleaning or replacing parts. In the case of a dishwasher wax motor failure, the entire vent assembly must be replaced. We highly recommend using a professional for such repairs so you don’t permanently break your home appliance. Appliance Repair Expert is a company that specializes in repairs of any complexity. Call us now and get your unit fixed on the same day.

Author: Jacob Dillard
My name is Jacob Dillard, and I am the author of articles at Appliance Repair Expert. Since childhood, I have been fascinated by technology and spent much time reading different books and trying to repair my first CD player. Then, I graduated from the University of Toronto with a degree in Applied Science and Engineering. In a year, I got my first job as a technician at an appliance repair company. After years of practice and working with professionals, I decided it was time to share my knowledge and experience here at Appliance Repair Expert. I want to help you understand everything related to appliance repair, maintenance and installation in the simplest way possible. It will be fun, believe me!

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