Customer Questions and Answers for Dryer Moisture Sensor Bar by Whirlpool

Jay, remove any clothes from the dryer, turn it on high heat and with a thermometer, check the air temperature coming out of the vent, it should read about 140-160 degrees F. If the temperature does not get that hot, relace the thermistor, WP8557403 located on the blower housing. If the temperature is correct, make sure there are no restrictions in the vent and that you have good airflow to the outside.

Mike, the sensor bars can be cleaned and then tested for continuity. Normally the sensor bars accumulate residue from dryer sheets and softeners that stop them from being able to work properly. Vinegar can help to remove any residues that may have accumulated. Once they are thoroughly cleaned, each bar would be tested for continuity from one end to the other. As long as they have continuity, they are good.

Hello Marlene, both the bars in the video make up the moisture sensor. Thanks!

Ed, You shouldn't need to replace the sensor bars, unless they are missing, they can be cleaned occasionally with an alcohol pad. To test them. place the meter leads on the sensor bar terminals, there should be an "open" circuit, place something wet or metal across the two bars, and the circuit should "close", it is an open circuit by design. Basically, wet articles falling or touching the sensor bars divert the circuit to chassis ground (a closed circuit) once the articles are dry, the circuit "opens" and allows the circuit to flow to the triac on the control board, the triac develops a "charge", when the charge builds up enough it opens and caused the board to signal the control to shut off. We don't see a need to replace anything at this point, the sensor has little or no effect on the heat cycle. You may want to recheck and clean the wiring and connections to the sensor bars and heater components.

Wendy, the sensor for your model is part number [33001809]. Unfortunately this part has been discontinued by the manufacturer and is no longer available.

Daniel, check the high limit thermostat, it has a yellow and white wire going to it, if it checks open for continuity, it will need to be replaced. Check the door switch as well. If the belt is broken, this model will not allow the motor to come on and run. If all these check ok, go to the main control board, press the start button, you should read 0 volts across the brown and black connections on the motor relay, if you read 120 volts, the relay is bad and the control would need to be replaced. Part number for the board is WP35001153, the thermal fuse is part number WP35001087, it is located on the blower housing.

Charlie, When replacing the moisture sensor bars it would be recommended to replace both of the bars.

Jerry, This error code is an indication of the moisture sensor being open. TEST #4 Moisture Sensor NOTE: This test is started with the dryer completely assembled. This test is performed when an automatic cycle stops too soon, or runsmuch longer than expected. NOTE: Dryer will shut down automatically after 2-1/2 hours. The following items are part of this system: Harness/connection Metal sensor strips Machine control electronics. See ESD information, page 1. 1. Enter Service Diagnostic mode and select the User Interface/Control System test. See procedure on page 5. 2. Open the dryer door. The dryer should beep and an alphanumeric number should be displayed (on models with seven segment display) or the TEMP, TEMP LEVEL, or DRY TEMP indicators should change (on models without seven segment display). 3. Locate the two metal sensor strips on the face of the lint screen housing. Bridge these strips with a wet cloth or finger.  If a beep tone is heard and an alphanumeric number is displayed on the console (on models with seven segment display) or the TEMP,TEMP LEVEL, or DRY TEMP and STATUS indicators change (on models without seven segment display), the sensor passed the test. Go to step 9.  If a beep tone is not heard, or a continuous beep tone is heard before bridging the moisture strips, continue with step 4. NOTE: Overdrying may be caused by a short circuit in the sensor system. 4. Unplug dryer or disconnect power. 5. Access the moisture sensor wires by removing the toe panel. Disconnect the sensor wires from the harness. See figure 11. 6.Access the machine control electronics. See Accessing & Removing the Electronic Assemblies, page 23. Remove connector P13 from the circuit board. Check the main harness connections between the sensor harness and machine control for a short or open circuit.  Replace the main harness, if necessary.  If harness is OK, continue with step 7. 7. Measure the resistance across the outermost contacts of the cable that includes the two red MOVs.  If a small resistance is measured, check for debris across moisture strips inside the drum; clean if debris is present. If debris is not present, replace sensor harness.  If a small resistance is not measured, continue with step 8. 8. Measure the resistance across each of the outermost contacts and the center terminal (ground connection).  If a resistance less than infinity is measured, replace the sensor harness. 9. Ifmoisture sensor diagnostic test passes, check the thermistor: PerformTEST #3a, page 19.  If the problem persists after replacing the moisture sensor and thermistor, replace the machine control electronics.

Daniel, Try to clean the sensor bars with rubbing alcohol and see if this does not correct the issue. If it does not then check the wiring between the sensor and the control board of the unit.

Brian, You will need to check the wiring to the sensor and if the sensor checks ok then this will be a faulty control board.