Technical Description
Malfunction in Vehicle Speed Sensor “A”
This diagnostic trouble code (DTC) is a generic powertrain code, which means it applies to OBD-II equipped vehicles, including but not limited to Ford, Toyota, Dodge, BMW, Subaru, Honda, Lexus, Mazda, etc.
Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
What does that mean?
In simple terms, the P0500 code indicates that the vehicle’s speed, as detected by the Vehicle Speed Sensor (VSS), is not as expected. The VSS input is used by the vehicle’s main computer, known as a PCM/ECM powertrain/engine control module, along with other inputs to ensure proper operation of the vehicle systems.
Typically, the VSS is an electromagnetic sensor that utilizes a rotating reluctor ring to complete an input circuit to the PCM. The VSS is positioned in the transmission housing in close proximity to the reluctor ring, which is attached to the transmission’s output shaft. As the reluctor ring passes by the electromagnetic tip of the VSS, the circuit is rapidly completed and interrupted through notches and grooves. The PCM recognizes these circuit manipulations as transmission output speed or vehicle speed.
Related trouble codes for the vehicle speed sensor:
A typical VSS or vehicle speed sensor:

Symptoms
Symptoms of a P0500 DTC may include:
Causes
A code P0500 may indicate one or more of the following:
Possible Solutions
As a vehicle owner or DIYer, it is recommended to search for technical service bulletins (TSBs) specific to your vehicle make, model, engine, and year. If a known TSB exists, following the instructions in the bulletin can help save time and money in diagnosing and repairing the issue.
Next, visually inspect all wiring and connectors that lead to the speed sensor. Thoroughly examine for any chafing, bare wires, broken wires, melted areas, or other damage. Repair as necessary. The location of the sensor depends on the vehicle and may be on the rear axle, transmission, or wheel hub (brake) assembly.
If the wiring and connectors appear to be in good condition, check the voltage at the speed sensor. The exact procedure will depend on the make and model of the vehicle.
If everything appears to be in order, replace the sensor.