One problem related to brake antilock wheel speed sensor 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.
The esc off light turned on by itself. When pushing the button for the esc off, nothing happened. A few days later I noticed a minor stutter-step of the car's forward motion with a slight grinding noise, and the esc off light was illuminated again. The esc off light stayed illuminated. When I arrived at my destination, I shut the car off then turned it on again. The esc light was no longer illuminated. August 27, 2014, I left my car at the dealership and proceeded to work, they "found damage to left-front wheel speed sensor and left-front tone wheel. They also stated both the speed sensor and left-front tone wheel need to be replaced before further diagnosis could be performed. August 30, 2014, I was traveling at approximately 40 m. P. H. When traffic ahead began slowing. I applied the brakes and the car didn't just stutter & grind, it was like one side of the vehicle wasn't braking at all and the other side was breaking hard. The car jerked side to side for a short distance then seemed to right itself. The esc off light was now illuminated again. If I had been traveling any faster, or in heavier traffic, this certainly would have caused me to have an accident. I feel this is a design flaw, not an error on my part as the consumer, and believe this to be a life and death safety issue. My brakes have never been worked on and there's no logical reason for the speed sensor and left-front tone wheel to be damaged.