One problem related to engine knocking noise has been reported for the 2006 Hyundai Sonata. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2006 Hyundai Sonata based on all problems reported for the 2006 Sonata.
In Jan. 2015 it was on a 100 mile highway trip. Upon arrival he noticed the engine developed a knocking noise. I found many 2. 4l Hyundai's with the same problem on the internet. The engine was made in indiana. It sounds the same as nhsta campaign #15v-568. It needs a new engine. I can't upload it, but I have video of the knocking. I believe the recall needs to be expanded to earlier years.