Some older-model Subarus, particularly 1999 models, were manufactured with faulty parts that lead to frequent speedometer failure. A vehicle's speedometer not only provides the driver with speed information, but also provides speed-related information to computers within the car that manage safety, efficiency, and convenience systems like power braking, fuel injection, cruise control, and more. Depending on the source of speedometer issues, either the speedometer alone or the speedometer and other systems together will malfunction.
The vehicle speed sensor is an instrument that records the timing and amount of the vehicle's wheels. The vehicle's computerized systems use the data to calculate speed and distance traveled. Most Subaru vehicles have multiple speed sensors. If one or more of the vehicle's speed sensors fail, the speedometer will typically show inaccurate speeds.
In addition to providing data for the speedometer, the vehicle speed sensors supply data which may also be used by systems such as the automatic transmission, cruise control, anti-lock brakes, power steering, and other systems.
The speed sensors can be replaced individually, or all at once.
Failure of the speedometer head is a relatively frequent problem with some models and model years. 1999 vehicles seem particularly prone to speedometer head failure. If the speedometer head fails, the speedometer will not show an accurate speed, the speed shown will jump around, or the speedometer will work only intermittently. The common solution to speedometer head failure is replacement of the speedometer head.
If the vehicle speed sensors and speedometer head all work individually, speedometer problems may lie with the cables that connect the separate pieces. Tracing the cables that connect to the speedometer and checking the tightness of all connections may help locate the source of failure.
