* Inaccurate speedometer: This is the most obvious symptom. The speedometer may read incorrectly, showing a speed that is higher or lower than the actual speed.
* Malfunctioning cruise control: Cruise control relies on the vehicle speed sensor to maintain a constant speed. A faulty sensor will likely prevent the cruise control from working properly, or cause erratic speed control.
* Transmission problems: The transmission uses the vehicle speed sensor to determine the appropriate gear ratios. A faulty sensor can lead to rough shifting, delayed shifting, inability to shift gears, or even transmission damage over time. This is particularly true for automatic transmissions.
* ABS (Anti-lock Braking System) malfunction: The ABS system also utilizes the vehicle speed sensor to determine wheel speed and prevent wheel lockup during braking. A faulty sensor can disable the ABS, making it harder to brake effectively in slippery conditions.
* Traction control problems: Similar to ABS, traction control uses wheel speed sensors to detect wheel spin and reduce engine power to regain traction. A faulty sensor can cause traction control to malfunction or not activate when needed.
* Check Engine light: A faulty vehicle speed sensor will almost certainly trigger a check engine light, storing a diagnostic trouble code (DTC) in the vehicle's computer.
* Incorrect fuel economy calculation: The on-board computer uses the speed sensor, among other data, to calculate fuel economy. A faulty sensor will lead to inaccurate fuel economy readings.
The severity of the problems caused by a faulty vehicle speed sensor varies. In some cases, it might only result in an inaccurate speedometer reading. In other cases, it could lead to serious safety issues, like a malfunctioning ABS system.
