How a washing machine pressure sensor works
Steven E / Thursday December 14, 2023
A washing machine pressure sensor is an important component that monitors and regulates water levels through the pressure hose as the tub fills. The washing machine control board and this sensor work together to make sure that the proper amount of water is used during the various wash and rinse cycles.
Understanding how a washing machine pressure sensor functions can help homeowners troubleshoot issues when the washer is not filling or draining correctly. Additionally, knowing how to locate, test, and replace a faulty pressure sensor can aid in do-it-yourself repairs, potentially saving time and money.
What does a washing machine pressure sensor do?
The main responsibility of the pressure sensor in a washing machine is to monitor the water pressure and water levels inside the tub. Here are the main functions of the pressure sensor:
- Tracks water level by measuring air pressure in the empty tub before filling. It then measures water pressure during fill. Converts pressure readings to electrical signals.
- Communicates pressure measurements to the control board to regulate water flow into the tub based on preset fill levels for different cycles or load sizes.
- Helps prevent overflowing by stopping water flow if the preset levels are exceeded.
- In a washer, the pressure switch and board may monitor the water level in the machine to confirm the water is draining properly.
- A cycle will stop if abnormal pressure readings occur until the underlying issue is corrected.
Essentially, the washing machine pressure sensor provides closed-loop feedback to ensure the right amount of water is used during the different wash and rinse cycles. Malfunctions with this component can lead to various operational problems.
READ MORE: How To Find Your Appliance’s Model Number
How does it work?
Washing machine pressure sensors use various mechanisms to detect changes in water pressure inside the washer tub and convert this to electrical signals for the control board. Here are some common pressure monitoring methods:
- Pressure Sensing Mechanism: Modern washing machines use a pressure sensor/switch. The sensor measures the air pressure developed in an air dome, which correlates with the water level in the machine. This method provides a fairly accurate measurement.
- Air Chamber and Pressure Switch: Inside the washing machine, there’s an air chamber connected to the water chamber. As the water level rises, so does the air pressure in this chamber. A diaphragm in the pressure switch responds to these changes in air pressure. When the desired water level is reached, the diaphragm activates a switch, signaling the control board to halt the water inlet valve. Conversely, if the water level is too low, the pressure switch will trigger the water inlet valve to add more water. This system ensures efficient water usage and prevents overflows.
- Electronic Pressure Sensor: Many washing machines, both top-load and front-load models, use an electronic pressure sensor instead of a mechanical pressure switch. This sensor communicates with the machine’s control board to regulate the amount of water entering the tub for wash or rinse cycles. It can be a standalone component or part of the control board. An air pressure tube connected to the tub and the sensor or control board helps in this process. As the tub fills, air pressure in the tube increases, and when a sufficient amount of water fills the tub, the pressure causes the sensor to signal the control board, which then shuts off the water.
READ MORE: Top 5 Tips for Troubleshooting Appliance Problems
Signs of a faulty pressure sensor
Since the pressure sensor plays an important role in controlling water fill levels in the washing machine, a malfunctioning sensor can cause several problems. Here are some typical signs of a bad or failing washer pressure sensor:
- The washer tub takes on too much or too little water for a given cycle.
- The washer overflowed with water and leaked onto the floor due to overfilling.
- The washing machine stopped mid-cycle due to incorrect readings.
- Failure to adequately drain water from tub and pump.
- Displays error code related to water pressure level.
- Poor wash performance from incorrect water amounts.
- Excessive suds and leaking caused the improper amount of rinse water to be dispersed.
Catching pressure sensor issues early can prevent more severe leaks, overflows, and failures. Always investigate any unusual fill or draining behavior promptly.
How to replace a faulty pressure sensor
When diagnostics confirm the washing machine pressure sensor needs replacement, follow these steps:
- Unplug the washer – Disconnect the power cord before starting to avoid electric shock.
- Turn off water supply – Shut off both hot and cold water lines to prevent leakage.
- Access sensor – Remove the console, front panels, and top as needed to access the sensor. Located on control housing, tub wall, or sump.
- Disconnect the pressure hose – This sometimes slides over a small lip or nipple on the sensor.
- Disconnect wiring – Detach sensor wiring harness or terminals. Make note of connections.
- Remove fasteners – Take out mounting screws or retaining clips to detach the sensor.
- Install new sensor – Secure the new pressure sensor and reinstall the pressure hose. Then, reconnect the wiring in proper order.
- Reassemble washer – Replace panels and parts in reverse order.
- Restore utilities – Turn on the water supply and plug in the power cord.
- Test operation – Run the washer through fill/drain cycles to verify the pressure sensor is working properly after the repair.
READ MORE: My part is no longer available! What do I do now?
Frequently asked questions
What are some common signs of a faulty pressure sensor?
Some common signs include the washer not filling properly, overflowing with too much water, stopping mid-cycle, failing to drain fully, displaying error codes related to water pressure, and having poor wash performance.
How can I test if the pressure sensor is working correctly?
You can test the pressure sensor by running a short fill cycle and determining if the washer fills to the correct level based on the cycle selected. The pressure readings should match the expected values.
Where is the pressure sensor located in my washing machine?
The pressure switch is typically located as part of the control board, in the control panel area, or attached to the inside of the machine cabinet. Check the part diagrams for your model’s exact location.
Can I clean or repair a pressure sensor rather than replace it?
In most cases, a failed or damaged pressure sensor will need to be fully replaced. But in some instances, debris or detergent build-up in the pressure hose may be cleared and cleaned.
Does water temperature affect pressure sensor accuracy?
Yes, pressure sensors have pre-calibrated operating ranges.
Is a pressure sensor the same thing as a pressure switch?
No, they are different components. A pressure sensor detects water pressure levels and converts this to electronic signals for the control board. A pressure switch is a mechanical on/off switch that is triggered to open or close an electrical circuit at specific pressure thresholds. Both monitor washer water levels.
More information
Thanks for reading! If you have any other appliance repair needs or projects, you can find more resources including our DIY blog at AppliancePartsPros.com. There, you can enter your model number to order the exact parts you need. Most orders arrive in two business days.
You can also reach our award-winning customer service team at 1-877-477-7278, chat with a pro on our website, and watch thousands of free video tutorials on our YouTube channel.
With nearly a decade of experience in providing top-notch customer service regarding appliance parts and repair, Steven enjoys sharing practical advice, troubleshooting tips, and interesting information to help readers stay informed.