Speedometer doesnt work and change everything you can think of on 2002 Jeep Liberty

(For my dad) may not have the wordung right so bare with me. Speedometer doesnt work and changed the wiring, plugins, checked fuses, tore the rearend apart and checked everything there, plugins by or on the transmission. Any ideas what else it may be? Also check engine light us on and reads PO500-speed sensor malfunction.

Asked by for the 2002 Jeep Liberty
Sorry, no response so removed answer... Seems you do not need any help!!