If the cluster messes up the computer will not receive the correct speed signal and performance will suffer especially if you have an automatic. The speed sensor sends a signal into the cluster and the cluster then conditions this signal and then sends it to the computer as a square wave equivalent to the analog signal coming from the speed sensor. If the cluster is defective the speed signal is still coming in but there is no square wave leaving thus the p0500 speed sensor code. (your speedometer may or may not be working properly when this occurs). Generally the speed sensor is not defective; the cluster is. We repair them visit Mr. Whizard Technical Services for more info.