Frigidaire dishwasher error code UO

All Frigidaire dishwasher models error code UO has similar manifestations: first, the wash tank filling system starts, then 3 – 4 clicks are heard, and error code UO appears on display. If you press Cancel, the dishwasher will drain water. But under the next switching on, the problem will happen again.

Frigidaire dishwasher error code UO

Error UO: description

This symbol combination stands for “Vent Open” – the display cannot display the letter V, so it changes it to U. The sound of tapping is heard when the solenoid makes several attempts to close the slider. In case of failure, the system does not receive the proper signal and generates error code UO.

An engine, a so-called wax motor, is responsible for the operation of the subunit. It is actuated and pushes the plunger, blocking the ventilation hole. At the beginning of the cycle, it must be closed so that the steam does not come out. The slider opens only in the drying mode, allowing the fan to “blow out” excess moisture.

But take your time changing the parts: electronically controlled devices sometimes give false signals. Unplug the dishwasher for 10 – 15 minutes and restart it. Check if error UO appears after reboot. For maximum accuracy, perform a diagnostic test by holding the Air Dry and Start buttons for 3 seconds. If the problem persists, the system will immediately report it.


According to the Frigidaire dishwasher manual, error code UO indicates a breakdown of the ventilation subunit or mainboard. The manufacturer suggests changing them to new ones – without checking and repair. But some users find more budget solutions, identifying the specific causes of the failure.

1. Faulty wiring and lose connections

A wire harness stretches from the fan, which goes to the control module through the bottom of the door. Check their integrity with a multimeter. Make sure that there is no corrosion on the electrical connectors that form when wet. It prevents the signal passage. The system does not receive a message that the ventilation hole is closed. Therefore it displays error code UO.

Clean the rusted contacts with a wire brush and treat it with dielectric grease. Fasten loose joints. Solder and insulate the wires in the area of ​​damage. If the harness cannot be restored, replace it.

2. Dirty valve or sensor

Before trashing the ventilation components, try to remove limescale and soap residue from them – perhaps after that error, UO will disappear. The node you are interested in is located in the upper right on the back of the dishwasher.

  • Unscrew the fixing ring. Turn over the vent and fan assembly.
  • Remove the two small screws to remove the cover. You will gain access to the rubber valve, which is opened/closed with a small solenoid.
  • Disconnect it and wipe it well. Be careful: there is a fragile plastic tab that controls the optical sensor – do not damage it!
  • Assemble the ventilation subunit by performing these actions in reverse order.

Sometimes it is not enough, and error code UO continues to appear. In this case, you need to clean the small optical sensor that tells the board about the position of the plunger. The sensor element, designated U1, is located on a flat plate at the back of the valve. Remove plaque from it using a nylon brush and lens solution.

3. Broken ventilation subunit

Relying on the manufacturer, this part of the dishwasher cannot be checked and repaired – the mechanism has been made maintenance-free. In the Frigidaire dishwasher, manual error code, UO only provides for the installation of a new ventilation assembly without identifying the reasons. Moreover, there are no guarantees that such a solution will help, because the next candidate for replacement may also be faulty – it’s a control board.

Some users have learned how to get around the “prohibition” of repairs on their own. It is effective if the optical sensor does not detect the position of the slider correctly and causes error code UO. To check it, you must:

  • make sure that the ventilation hole normally closes at the beginning of the cycle;
  • access the assembly and remove the U1 element from the circuit board behind the valve;
  • install a new sensor that costs less than a dollar (from 85 cents).

A suitable replacement part is the EE-SX1105 Omron (phototransistor output, 2 mm Slot Type 30V). The wires that go to the circuit board will have to be cut and then soldered back.

But the engine may also be problematic. If the wax motor fails, the plunger will not close the slider, wherefore error UO will disappear. This element is not repairable – you need to change the entire subunit as an assembly. Its cost depends on the type of dishwasher. Some models need a kit of a fan and wiring harness for $ 175 (part number 5304467317). The others only need a ventilation system for $ 70, without wiring (number 154861101).

4. Problematic control module

This is the next part that Frigidaire proposes to replace. To access it, unscrew the fasteners on the front of the dishwasher, remove the door panel, and the waterproof coating. Examine the mainboard for corrosion and damage. Restore burnt-out paths, re-solder inoperative components. In extreme cases, install a new module, which costs about $ 115.

Author: David Hoover