What are the symptoms of a faulty Volkswagen wheel speed sensor?
2 Answers
Volkswagen wheel speed sensor failure symptoms include the ABS being unable to receive signals. When the wheel speed sensor malfunctions: The ABS module cannot receive correct signals from the wheel speed sensor, which will generate fault codes and trigger warning lights on the dashboard. If you suspect a sensor failure, you can perform the following measurements to determine whether the sensor is faulty and unable to send correct signals to the ABS module. Further diagnosis: Check if the sensor is a two-wire Hall-effect wheel speed sensor. You can use a multimeter set to the 2K resistance range to measure the sensor's resistance. A two-wire Hall-effect wheel speed sensor will show infinite resistance. When using the diode test function, there should be a voltage drop of 0.3V-0.7V. If the multimeter in 2K resistance range shows a resistance reading between 1K-1.6K, this indicates a magnetic induction type sensor. Testing sensor signals: Hall-effect wheel speed sensors output square wave pulse signals with strong anti-interference capability. Typically, use an oscilloscope probe's hook to clamp the signal wire and the black clamp to ground on the vehicle body. When rotating the signal disk, you should observe a square wave signal waveform between 0.5V-1.5V. Sensor data stream comparison method: Access the ABS module to read sensor data streams. During a road test, observe and compare the suspected sensor's data stream with the other three wheel speed sensors. This method can be used for intermittent fault detection.
Having worked in car repairs for many years, I often hear Volkswagen owners complain about similar issues. When the wheel speed sensor fails, the most obvious symptom is the sudden illumination of the ABS light on the dashboard, sometimes accompanied by the ESP light. This happens because the sensor monitors the rotation speed of each wheel, and once it malfunctions, the system can't function properly. While driving, you might notice the speedometer needle jumping erratically or displaying incorrect values, such as showing 0 when you're actually at 60 km/h. Even worse, the ABS anti-lock braking system fails, increasing braking distance and making the car more prone to skidding in rainy conditions. It may also affect the transmission, causing rough shifting or triggering limp mode, which limits engine power. I recommend not waiting and taking the car to an authorized repair shop immediately for inspection. Replacing the sensor is quick and inexpensive. Ignoring the issue can lead to a chain reaction, such as damage to the ABS pump, which would be much costlier to repair.
