What size socket do I need to replace the crankshaft position sensor?

Hello, I'm sorry, there is no manual that will tell you this information. If there is a Kia tech familiar, maybe they can weigh in. However, the crankshaft position sensor doesn't often need to be replaced. The diagnostic trouble code that comes up is likely not related to a problem with the sensor. Testing is needed to find out what's going on. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops