I have not experienced any problems that I can recall but my ESC OFF light came on and then not long after that the check engine light came on. When taking it into the dealer today, did not know it would cost $106 for diagnostic so I didn't do it. Took it Auto Zone and they did it free and came up w/ P0504 and P0571 for the car which didn't really come up w/much. When got home and did some searching on the internet, I found, it is probably a "stop lamp" or brake switch replaced. Any further guidance would be appreciated. Thanks, Kim Herman

It's possible that the front suspension replacement could have contributed to the ESC malfunction. The ESC system relies on input from various sensors to determine the behavior of the vehicle, including sensors related to the suspension and steering. If these sensors are not functioning correctly or providing incorrect information, it can trigger the ESC and check engine lights to come on.
In this case, I would recommend having a professional mechanic perform a thorough diagnostic to determine the root cause of the issue. They may need to check the wiring and connections related to the front suspension and any sensors involved in the ESC system.
If the problem persists even after a thorough diagnostic, it may be worth reaching out to Hyundai customer service to see if there is any other potential solution for your particular vehicle. It's possible that there is a known issue with the 2006 Sonata that is not covered by the recall but can still be addressed by the manufacturer.

I DON'T KNOW - CONSIDER NEUTRAL SWITCH MAY BE PROBLEM. IF EQUIPPED WITH SHIFT LEAVER, VIGOROUSLY MOVE THROUGH ALL POSITIONS ABOUT 6 TIMES, TO SEE IF THAT CURES THE PROBLEM.
YOU DON'T WANT TO BE STUCK AND THIS NEEDS TO BE REPAIRED. ASK DEALER IF THERE IS A RECALL. DEALER MAY OFFER DIAGNOSTIC SERVICE. ANY MECHANIC MAY BE ABLE TO CHECK LIGHT CODES FOR CAUSES.

https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CCoQFjACahUKEwiS14u9h4fIAhVD2D4KHRmyDSo&url=http%3A%2F%2Fwww.hyundai-forums.com%2Fentourage-forum%2F147913-tps-sensor-symptoms-tps-failure-cel-esc-off-light-%253Dtotal-loss-power.html&usg=AFQjCNGoQ6TzxEEYpOh0X7Cj2X-lQjPDMQ There are many web sites that refer to the problem you are experiencing

You'll need to have someone scan the engine and body computers to get the trouble codes. The ESC and ABS could be on because of a problem connected to the engine computer, or they could have their own issues in addition to the engine. All three systems work together.

The ESC Off light comes on and pushing the ON/OFF switch does not put it out. If I shut the car off and re start, the dash light goes out sometimes; May return the next time I start the car..I've heard that the problem has something to do with the brake sensors. People usually notice that the brake lights go crazy as well.My 2009 is in the shop right now for my check engine light. My ESC light is also coming on as well. They ran the diagnostic and the only code that showed up was a faulty crankshaft sensor. I'm wondering if that is affecting the ESC. I know when the ESC comes on I get hesitation before it. That might be the crankshaft sensors doing. They said no other codes came up.This problem was recalled back in 2007-2008 and is presently being recalled on some vehicles. This appears to be a common problem with Hyundais who refuse to address the problem unless the cars are recalled. Please write the National Car Safety so that they can request a recall. Without these complaints, the recall will not occur and everyone will be paying out of pocket for a manufacturing defect.

https://www-odi.nhtsa.dot.gov/ivoq/

The brake light recall you got in the mail should fix the ESC light.

HYUNDAI IS RECALLING 532,633 MY 2006-2007 ACCENT, ENTOURAGE, SONATA, MY 2007 AZERA, ELANTRA AND SANTA FE, MY 2005-2007 TUCSON AND MY 2007-2008 VERACRUZ VEHICLES. THE STOP LAMP SWITCH IN THE AFFECTED VEHICLES MAY MALFUNCTION. A MALFUNCTIONING STOP LAMP SWITCH MAY CAUSE THE BRAKE LIGHTS TO NOT ILLUMINATE WHEN THE BRAKE PEDAL IS DEPRESSED OR MAY CAUSE THE BRAKE LIGHTS TO REMAIN ILLUMINATED WHEN THE BRAKE PEDAL IS RELEASED. A STOP LAMP SWITCH MALFUNCTION MAY ALSO AFFECT THE OPERATION OF THE BRAKE-TRANSMISSION SHIFT INTERLOCK FEATURE SO THE TRANSMISSION SHIFTER WOULD NOT BE ABLE TO BE SHIFTED OUT OF THE PARK POSITION. IT MAY ALSO CAUSE THE ELECTRONIC STABILITY CONTROL (ESC) MALFUNCTION LIGHT TO ILLUMINATE, AND IT MAY NOT DEACTIVATE THE CRUISE CONTROL WHEN THE BRAKE PEDAL IS DEPRESSED.

The stop lamp switch is used to judge if the acceleration system is abnormal. The stop lamp switch contains two switches monitored by the PCM. This is all covered at the dealer.

The stop lamp switch contains two switches monitored by the PCM. This will cause the issue you are having. It will illuminate the engine light also and cause the transmission to go into limp mode which is what's happening. Have replaced many for this same exact issue. This is what needs to be done next. The engine and ESC light come on together.

Hope this helps; also keep in mind that your feedback is important and I'll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using Fixya, and have a nice day.

When a 'check engine light' (MIL=Malfunction Indicator Lamp) is turned on, there is a DTC (Diagnostic Trouble Code) set/stored in the ECM/PCM (Engine Control Module/Powertrain Control Module). This code identifies which engine management system component/function experienced a malfunction. Once you pull/read this code, you may begin diagnosis.

I had this exact same problem...turns out it has to do with a recall having to do with the stop lamp switch. I took it to the dealership and it only took about 20 minutes form them to fix it.
Hyundai is recalling 531,894 MY 2006-2007 Accent, Entourage, Sonata, MY 2007 Azera, Elantra and Santa FE, MY 2005-2007 Tucson and MY 2007-2008 Veracruz vehicles. The stop lamp switch in the affected vehicles may malfunction. A malfunctioning stop lamp switch may cause the brake lights to not illuminate when the brake pedal is depressed or may cause the brake lights to remain illuminated when the brake pedal is released. A stop lamp switch malfunction may also affect the operation of the brake-transmission shift interlock feature so the transmission shifter would not be able to be shifted out of the park position. It may also cause the electronic stability control (ESC) malfunction light to illuminate, and it may not deactivate the cruise control when the brake pedal is depressed. Any of these malfunctions, alone or in combination, may lead to a crash. Dealers will replace the stop lamp switch free of charge. The recall began on April 23, 2009. Owners may contact the Hyundai Customer Assistance Center at 1-800-633-5151. This recall was the result of a Preliminary Evaluation conducted by the Office of Defects Investigation.

My car is having the same problem, and I've heard it's a defective stop lamp switch, which there is a recall on, and the dealer will fix for free. The recall ID# 09V122000 number to call listed with recall info #1-800-633-5151 http://www.automotive.com/hyundai/sonata/2006/recalls/t3-12-2-1/

esc is electronic stability control. without the abs sensor working the esc can not work proper as it can not read the wheel speed.
it has nothing to do with the stop lamp