P0500 is a OBDII trouble code that affects the Saab 9-5‘s Vehicle Speed Sensor (VSS). The VSS sends a signal to the engine’s computer letting it know how fast that the vehicle is going.
The 9-5 uses this signal for many vehicle functions. It helps control transmission shifts, ABS, cruise control, the speedometer, and more. Fixing it should be considered a priority.
Saab 9-5 P0500 Symptoms
Symptoms will vary depending on the model year and other conditions. But, these are the most common symptoms of P0500 in general.
- Speedometer Failure– Without a properly working vehicles speed sensor, the speedometer will not register any speed. It’ll just sit at 0 MPH while you are driving. The Odometer may not work at all.
- Cruise Control Failure– When a vehicle is not getting a signal from the VSS, it’ll not let the cruise control engage. This makes sense since it can’t control the speed when it doesn’t know how fast it is going.
- Harsh Shifts- The transmission may shift differently than it normally does.
- Anti-Lock Brakes– The 9-5’s ABS may not work or could be compromised. The VSS is one component of a complicated set of sensors that keeps the wheels from locking under heavy break pressure.
P0500 Causes: Saab 9-5
- Bad VSS– More often than not, when P0500 is thrown, replacing the Vehicle Speed Sensor will remedy the problem. They are pretty affordable too.
- Wiring Problem– Due to the location of the VSS, the wiring harness going from the vehicles computer to it can often become damaged and open/short out. When this is the case, the 9-5 will no longer be able to determine what the VSS is reading. If you can safely take a look at the harness, that would be a great place to start. Make sure that it is plugged in all of the way. From there, check and see if any of the wiring is frayed. Here’s how to check for a short (YouTube).
- Tires– On some vehicles, P0500 can be thrown if the tires have been swapped to a size that is different from the factory setting.
The P0500 causes listed above are going to be the reason the code has been thrown most of the time. It is possible that the ECM/PCM has gone bad. That is the last place to look, not the first.
Due to the location of the VSS, the wiring harness leading to them can often fail. So, replacing it without inspecting it can be a mistake.
It would be best to start with inspecting the Wiring Harness first. If all looks good, take a look at the VSS itself. Does it have any noticeable damage?
Once you have done that (or even before if you happen to have a good scan tool) it’s time to test the sensor and see if the VSS signal goes up and down with the vehicle speed. If it doesn’t, replacing the sensor could fix the problem. If it does, you’ll have to test the rest of the circuit.
Diagnosing P0500 in the Saab 9-5 can be challenging. Don’t skip checking the wiring harness first. Good luck!