Speedometer Inaccurate
WARNING: This page is about a different car, the 1994 Oldsmobile Cutlass Ciera. However, it is still accessible from the selected car via links, so may be relevant.
Connect scan tester to DLC connector. Drive vehicle and compare scan tester speed display to instrument cluster speed. If both speeds agree, check tire size, PCM, and vehicle speed sensor. If both speeds do not agree, replace IPC.