A sensor, located on a vehicle's transmission / transaxle and not a part of the ABS system, used to measure transmission / transaxle output or wheel speed.

SPEED SENSOR

Fits C70, S60, S80, V70, V70 XC, XC90

Vehicle Speed Sensor
Your vehicle speed sensor sends information to your speedometer and/or your engine’s computer to tell the transmission when to shift. If the speedometer in your 2004 Volvo V70 isn’t working, or there’s a check engine light that accompanies shifting problems, let a Volvo technician examine your vehicle.