This transmission speed sensor monitors the rotational speed of the gearbox output shaft and sends a pulsed signal to the engine control unit. It is an inductive pickup that sits in the transmission housing, reading a toothed wheel on the shaft. A failing sensor produces erratic or missing speed readings, which can cause incorrect gear-shift timing and trigger diagnostic trouble codes. The sensor is built to the original electrical and mechanical specifications, ensuring the signal amplitude and frequency match what the control unit expects. On installation, ensure the sensor tip is clean and that the mounting bore is free of debris; torque the retaining bolt to the specified value.