For Kenmore 110.87872602, since Timed Dry works and heats normally, but Auto Dry counts down too quickly, and you’ve already replaced the moisture sensor bars, sensor harness, and control board, I would stop replacing moisture-sensing parts for now.
The next thing I’d check is whether the dryer is actually seeing the wet clothes against the sensor circuit.
Quick moisture-sensor test
Put several very wet towels in the dryer and start an Auto Dry/Sensor cycle.
After it begins tumbling, watch the estimated time. With genuinely wet laundry repeatedly contacting the sensor bars, the dryer should recognize moisture and prevent the cycle from rapidly advancing toward completion.
If it still races toward the end, we need to determine whether the sensor circuit is reaching the control correctly.
Test the sensor circuit with a meter
Unplug the dryer first.
Disconnect the moisture-sensor circuit from the control/harness and measure through the sensor circuit.
With nothing touching the sensor bars, you should essentially have:
OL / open circuit
Now bridge both sensor bars with a wet cloth or wet fingers. You should see continuity/resistance appear. The exact resistance can vary considerably depending on how wet the material is—the important thing is that it changes dramatically from open to a measurable resistance when moisture bridges the bars.
Since you’ve already replaced the bars and their local harness, pay particular attention to the wiring between that harness and the main control. Check each conductor end-to-end while moving the harness around. You’re looking for an open wire, loose terminal, backed-out connector, or poor connection.
Also check airflow through the dryer itself
Even though the house vent is clean, do one Auto Dry test with the vent completely disconnected from the back of the dryer.
If Auto Dry suddenly behaves normally, there’s still an airflow restriction somewhere downstream.
Also verify that the blower housing, lint screen duct, blower wheel, and internal exhaust passages are clear. A loose blower wheel can cause problems even with a perfectly clean external vent.
One important clue: the heating-element replacement
Because this problem changed after replacing the heating element, I’d inspect that repair carefully.
Make sure the element isn’t grounded to its metal housing. Unplug the dryer, disconnect the element wires and check:
- Element terminal → element terminal: should show normal element resistance, typically roughly 8–12 Ω.
- Either element terminal → metal heater housing: OL / no continuity.
If either terminal has continuity to the heater housing, the element is grounded and needs to be corrected/replaced.
I’d also inspect every connector that was disturbed during the element replacement, particularly the thermistor and thermal-device wiring around the blower/heater area.
My order of diagnosis
I would do the tests in this order:
- Very wet towel test on Auto Dry.
- Meter-test the moisture sensor circuit from the control end, not just directly at the bars.
- Run Auto Dry with the exhaust disconnected.
- Check the new heating element for a ground to its housing.
- Inspect the exhaust thermistor and its wiring/connectors.
Given everything you’ve already replaced, I would not replace another control board or another set of sensor bars. At this point I’m looking for a sensor-circuit wiring problem, incorrect temperature information reaching the control, airflow issue inside the dryer, or something associated with the recent heater repair.