Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2006 Hyundai Sonata owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2006 Hyundai Sonata. The contact stated that while driving at an undisclosed speed, the vehicle experienced a loss of automotive power. No warning light was illuminated. The contact was able to pull over to the shoulder of the roadway and noticed that engine oil was leaking onto the ground and the coolant level was abnormally low. The contact stated that the vehicle failed to restart and was towed to a local independent mechanic, where it was diagnosed with a valve cover leak. The vehicle was repaired at the owner's expense; however, the failure reoccurred. The local dealer was not contacted. In addition, the contact stated that several other unknown repairs were made; however, the failure reoccurred. The contact related the failure to an unknown NHTSA Campaign; however, the VIN was not included. The manufacturer was made aware of the failure. …
I am filing this complaint regarding a serious engine issue with my 2006 Hyundai Sonata equipped with a 2.4L GDI engine. My vehicle experienced [engine knocking, stalling, and then seized up indicating complete Engine failure] without warning, posing a potential safety hazard while driving. The issue appears to be identical to the known manufacturing defects that Hyundai has acknowledged in its recall of 2013-2014 Sonata models with the same engine Class Type. Although my vehicle is not currently included in the official recall " SONATA ENGINE RECALL CAMPAIGN it contains the Theta II MPI Engine which constitutes and Further solidifies proof of the ongoing Manufacturing Defects of Theta Model Engine design and exhibits the same symptoms of sudden engine failure. This raises concerns that the defect may affect a broader range of model years than Hyundai has acknowledged. …
May 2019: Battery light came on and off for a few minutes. Car sputtered and engine quit. Replaced alternator and battery; problem went away. Feb 2022: Battery light came on and off for a few minutes. Car sputtered and engine quit. Replaced alternator and battery. This time the mechanic noticed that oil was leaking from the front valve cover gasket and was getting into the alternator; thus the most likely source of damage to alternator.
Tl* the contact owned a 2006 Hyundai Sonata. While driving highway speeds, the vehicle made an abnormal noise and smoke emitted from the engine compartment. The failure occurred without warning. The contact was able to safely maneuver from the highway to a parking lot. The contact exited the vehicle and observed flames underneath the vehicle. The fire department was contacted and extinguished the fire. The vehicle was towed to a salvage yard where it was deemed a total loss. The dealer and manufacturer were not notified. There were no injuries. The contact stated that the vehicle was included in NHTSA campaign number: 18V026000 (service brakes, hydraulic). The failure mileage was approximately 100,000.
A fire started in the engine of my two-month-old 2006 Hyundai Sonata after it had been parked for approximately five hours. On the night that this happened, I had driven my Sonata three hours from atlanta, ga to albany, ga and parked in my driveway at about 5:30 pm. I subsequently ran a local errand and parked my car for the evening at 7:30 pm. The car was parked about 2.5-3 feet behind my mother's 1994 Chevrolet corsica. Around 12:30 midnight, my next door neighbor was banging on my window, yelling, "you have to get out of the house, your car is on fire!" flames shot up 5-6 feet in the air and ignited the trunk of my mother's car. Trees nearby were singed, and melted metal and rubber damaged the driveway. Thanks to my neighbor's quick action, the flames did not reach the fuel tank of my mother's car or our house, thereby averting a real disaster. …
I was driving home and slowed to let someone in front of me turn left into a grocery parking lot. The car suddenly started surging mad I could not stop it with the brake pedal all the way to floor. However, I did hit the car in font of me, with no damage to her car. I had popped the front right side of the bumper on my car. So we went on with our business when she found no damage to her vehicle. I had to turn the car off to stop the car from moving. I called the dealer glenn Hyundai and told them of the incident, they in turn told me this would be nearly impossible for this to happen! It did happen!! They called me after receiving the vehicle via tow truck and told me the throttle was dirty and needed to be cleaned. So I told them go ahead and then about half hour later they called and said the car needed a throttle position assembly replaced. …
At approx. 79K miles, when vehicle was turned on you could hear a mild knocking noise, and then it would fade. Took to dealer they could not identify the problem. At approx. 96K miles vehicle was driving on highway and vehicle shut off. Could not restart. Towed the vehicle after wards vehicle started up and knocking noise got louder. The noise is now on all the time and has a cyclic knocking noise from the engine. Advised manufacturer of other problems with vehicle in July of 2015. The engine stall happed in mid aug of 2015. Had vehicle diagnosed on aug 27, 2015. I have uploaded that diagnosis. Dealer advised possible metal debris, but said I would have to pay addistional fees to determine the cause. The diagnosis states the same problems as the NHTSA campaign number: 15v-568 and Hyundai campaign # 132. Loud tapping noise when running coming from bottom end rod. Need engine replaced. …
Purchased this Sonata used 3 months ago with 45,800 miles on it, drove it 4,000 miles and it developed a engine ticking noise which now has turned into a knocking sound at 1800 rpms goes away, then comes back at 2200 rpms. I contacted Hyundai customer service to establish a case number. The dealer has removed the oil pan and found shavings saying it needs a "short block" motor replacement at a cost of $5,800. Hyundai motor America denied the request for repair totally. I find that at 50,000 miles and being only the second owner, this motor had a defect that should be acknowledged as a defect and they should stand behind there product! This is my third Hyundai, new 2005 and new 2007 and I'm seriously in the market for a new SUV but if Hyundai won't stand behind a costly defect like this they will loose a 10 year very loyal customer forever.
On lambda/lambda ii mpi series engines, engine oil can leak onto the alternator, which could affect charging system function and potentially cause the engine to stall and not restart. This would result in a loss of motive power as well as affect power braking and power steering system function, which would unexpectedly increase steering and brake pedal effort, potentially increasing stopping distances and the risk of a crash causing injury and/or damage to property. Every make/model of vehicle that has this engine has oil leaks on the alternator and other critical components (I've replaced 3 alternators so far! ~$200 each! + labor!!!) yet only a certain year of the "vera cruz" received a recall because the cost to Hyundai would be higher to fix this issue on all affected vehicles (azera, sante fe, and my Sonata etc. Models)
The car was expertly maintained, followed the severe duty maintenance schedule. Never had a problem until 125,000 miles. Metallic debris in the crankcase caused the oil pump not to spray oil onto the connecting rod bearing causing a complete engine failure. This is the same thing that was recently recalled on the newer 2011-up theta ii. The theta I and theta ii are the exact same short blocks except for the theta ii's direct injection system. My mechanic who did the repair was very surprised since he always inspected my car annually and knew I used to be a mechanic and maintained all my cars like clockwork. The repair cost was $4,113.53, see attached invoice. The existing recall should be for all theta engine since 2006-up not just for the 2011-up.
NHTSA investigations
Loss of Motive Power
The National Highway Traffic Safety Administration (NHTSA) received a letter dated July 13, 2022, petitioning the Agency to initiate a safety defect investigation into loss of motive power allegations attributed to oil drain pan assembly failures on certain Hyundai Motor America, Inc. and Kia America, Inc. vehicles spanning Model Years (MY) 2005-2021.
Engine complaints in other Sonata years
Frequently asked questions
How common are engine problems on the 2006 Hyundai Sonata?
NHTSA has 73 complaints about the engine & cooling of the 2006 Hyundai Sonata, 7% of the model year's 1,047 complaints. The component named most often is engine (6 mentions).
Is there a recall for 2006 Hyundai Sonata engine problems?
No. NHTSA lists no engine & cooling recall for the 2006 Hyundai Sonata, though it has 9 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2006 Hyundai Sonata engine problems start?
Half of the complaints with a recorded mileage happened before about 75,000 miles, and 15% before 25,000 miles.
Is it dangerous?
Owners linked 2 crashes, 4 fires and 8 injuries to engine & cooling problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.