One problem related to engine knocking noise has been reported for the 2006 Kia Motor Optima. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2006 Kia Motor Optima based on all problems reported for the 2006 Optima.
After a recent oil change, the car was running horribly, making a knocking sound. Had an episode where the oil light was flashing on and off and the engine about died, so I had made an appointment for the vehicle to get checked for Monday morning. The Saturday before, while running errands, had the episode occur again, but this time, the engine locked up and it has been sitting at the dealership every since because although I have a manufacturer warranty, kia won't honor it with all my oil change receipts. I am frustrated, because I know others have had the same issue I have and haven't complained loud enough or whatever, but this is an issue with the engine, not me. No car should blow an engine at 62k. It's ridiculous.