I’m not familiar with the Subie Seat Track feature, so can’t offer much help on that. wheel speed sensor problems are best diagnosed with the Subie scan tool. The shop will put it on a lift and hand spin each wheel and look at the scan tool display result. That will usually show which – if any – of the sensors is faulty. If you are a diy’er, crawl under each wheel and make sure all the sensors are connected to the wiring harness robustly. If you want to play scientist its usually possible to connect an ac volt meter to a sensor and spin the wheel by hand to see if it is producing a voltage signal or not. The sensors operate on the principle of magnetic induction and are usually just a small coil of wire that produce an ac voltage in the millivolt range as the magnet in the hub gadget whirls past the sensor as the wheel spins.