One problem related to catalytic convertor has been reported for the 1999 Kia Motor Sephia. The most recently reported issues are listed below.
I own a 1999 kia Sephia and my daughter uses it at school. The problem is that kia will not honor the warranty for the repair of the catalytic converter. The case ref nbr is k1085742. Many reason were given, all relating to a manual engine flush, coolant flush,etc. My research shows that there is no correlation between the defective part and the selected maintenance item. My daughter should not have paid for the converter. (also they are about 50% of their cost on the open market).