Symptoms of a faulty speed sensor. Your vehicle’s engine management computer is responsible for monitoring speed. It needs to know the car’s travel speed to make decisions regarding transmission gear shifts and the operation of the cooling fan, among other things. This essential data is typically provided by the vehicle speed sensor (VSS), which is located on the transmission.
1. Malfunctioning Speedometer and Odometer
The most obvious symptom of a bad speed sensor is a speedometer that doesn’t work or gives erratic readings. The odometer, which records the distance traveled, may also stop functioning correctly.
2. Gear Shifting Issues
A transmission that shifts poorly, slips, or jerks can be a sign of a faulty speed sensor. The computer, deprived of accurate information, can no longer properly manage gear changes.
3. Check Engine Light Comes On
A failing speed sensor sends incorrect data to the engine computer. The computer detects an anomaly and illuminates the malfunction indicator (Check Engine) on your dashboard.
4. Loss of Cruise Control
The cruise control relies on information from the speed sensor to maintain a constant speed. If the sensor is faulty, the cruise control system is often disabled for safety and will no longer function.
What to do if symptoms appear?
If you notice one or more of these signs, it is advisable to have your vehicle diagnosed by a professional. They can confirm the fault using a diagnostic tool and proceed with replacing the sensor if necessary.