Subaru owners are often long-term brand loyalists who research their vehicles carefully — they'll come in with a printed forum thread and a theory. That's fine. What matters is that the diagnosis comes from the vehicle's data, not the forum. Here are the three misdiagnosis patterns I see most on this platform. 1. "Humming or droning noise at 35–55 mph" — secondary pulley bearing misdiagnosed as wheel bearing or tire noise. This is the one that fills alignment and tire shop appointment books, especially in winter when road noise provides cover for the symptom. Secondary pulley bearing failure on the TR690 produces a speed-dependent hum or drone — it changes with vehicle speed, not engine speed or steering input. Wheel bearing noise also changes with vehicle speed, which is why the misdiagnosis happens. The differential: wheel bearing noise typically changes when you apply a side load (turning left or right shifts the load off or onto a worn bearing). CVT secondary bearing noise does not change with steering input — it's consistent regardless of turn direction. If the noise is perfectly consistent under all steering conditions at a given speed, go to the CVT before pulling a wheel bearing.
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Subaru Lineartronic CVT Primary Pulley Position Sensor — TR690 Compatible
Replaces the failed position sensor that causes TR690 limp mode — confirm via primary pulley speed PID before ordering to avoid replacing a functional sensor.
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