What 758 owners told NHTSA about the 2017 Hyundai Sonata

My 2017 Hyundai Sonata SE, equipped with the Theta II 2.4L GDI engine, is experiencing severe powertrain failures including rhythmic metallic engine knocking, catastrophic oil consumption, and un-commanded surges/jumping in speed while driving. These symptoms manifested following an unauthorized engine replacement performed by Hyundai of El Cajon under Repair Order [XXX], where the dealer covertly outsourced my vehicle to a third-party shop (Legacy Motor Works) to install an unverified used salvage engine block rather than a certified factory assembly. This vehicle is a Class Vehicle under In re: Hyundai and Kia Engine Litigation (Case No. [XXX]), and the KSDS software update (Campaign 953) was successfully completed on my vehicle in 2019. The engine knock, surging, and oil consumption are consistent with the known connecting rod bearing failure defect described in NHTSA investigation PE17-007. The dealership is currently denying warranty coverage, citing a mileage limit that does not exist under my Lifetime Powertrain Warranty, and they are withholding physical documentation of the repair terms. The vehicle is also experiencing secondary safety failures, including a continuous airbag SRS warning light (two years) and electrical shorts caused by the salvage-yard alternator installation, which have destroyed 4 to 5 car batteries. This engine failure represents a significant safety hazard, as the vehicle periodically loses power and surges without driver input. I am requesting that NHTSA investigate this pattern of warranty denial, parts-sourcing fraud, and the safety risks posed by this substandard engine installation. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11745609

[XXX] [XXX] [XXX]; [XXX] [XXX] [XXX] Date: XXX To: National Highway Traffic Safety Administration Office of Defects Investigation (ODI) Subject: Formal Safety Defect Complaint – 2017 Hyundai Sonata Theta II Engine Failure, Excessive Oil Consumption, Intake/Engine Component Failure and Safety Hazard Dear Sir or Madam: I am submitting this formal complaint and request for immediate investigation into the dangerous and ongoing mechanical failures involving my 2017 Hyundai Sonata equipped with the Theta II engine. I believe this vehicle contains a serious manufacturing and/or engineering defect that presents a substantial safety hazard to consumers. My vehicle has experienced a pattern of progressive mechanical failure beginning with abnormal and excessive oil consumption, which appears to be directly associated with malfunctioning engine airflow and intake-related components. Specifically, the lower engine airflow system and intake functionality appear defective, placing excessive strain on the intake manifold system and contributing to cascading engine failures. As a result of these failures, the vehicle has experienced: Severe and excessive oil burning/consumption Intake manifold malfunction and abnormal operating stress Suspected overheating and/or premature head gasket failure Ignition coil failure and electrical shorting/misfires Progressive engine deterioration rendering the vehicle unsafe and unreliable Increased risk of sudden engine shutdown, stalling, fire hazard, or catastrophic engine failure while operating The vehicle has become increasingly unreliable and inoperable due to these conditions. These failures raise significant concerns regarding public safety, especially given the known history of complaints and recalls associated with Hyundai Theta II engine defects. I am deeply concerned that this vehicle may reflect a broader pattern of defective manufacturing, insufficient quality control. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11742419

My vehicle has a documented excessive oil‑consumption defect. After a 1,000‑mile oil‑consumption test performed by a Hyundai dealership, the engine was found to have consumed 2.8 quarts of oil, which is far above normal and poses a safety risk. The dealer referenced TSB 23‑EM‑008H and recommended a chamber cleaning but could not guarantee it would resolve the issue. Hyundai Motor America declined to cover the repair and refused to escalate my case. This level of oil consumption is consistent with known Theta II engine defects that have led to engine seizure, stalling, and fire in other vehicles. I am reporting this as a safety concern due to the risk of sudden engine failure while driving.

NHTSA ODI 11711950

Airbags did not deploy no indicator light came on before nor after I was struck from my driver side front area and yes it is available for inspection upon request. My safety along with my sisters safety was put at risk due to the negligence and cheapness of the dealership I purchased the car from also from there misleading information and improper inspection before selling me the car Car has not been reproduced or confirmed The car was inspected by a third party appraisal company for damages amounts There were no lights on at all before the accident and I am pretty certain that the dealership cleaared the codes before selling me the car

NHTSA ODI 11708579

e vehicle is burning approximately 2 quarts of oil every month with no external leaks. This indicates severe internal oil consumption, which is a known defect in Hyundai’s Theta II 2.4 GDI engines. I discovered oil inside the VVT solenoid electrical connector and on other wiring, which shows oil is traveling through the engine harness. This causes hesitation, rough running, and the risk of sudden engine power loss. The vehicle feels unsafe to drive because the oil level drops quickly, and the engine could seize or stall while driving. Hyundai vehicles of this generation have a history of excessive oil consumption, piston ring failures, and engine fires, and I believe my vehicle is experiencing the same defect. This is a serious safety concern.

NHTSA ODI 11702016

What component or system failed or malfunctioned, and is it available for inspection upon request? The engine in my 2017 Hyundai Sonata Sport is defective. Oil pressure failed testing, oil contamination was found on the oil pressure sensor and connector, and the vehicle has experienced excessive oil issues. The engine is still in my possession and available for inspection upon request. How was your safety or the safety of others put at risk? The vehicle has gone into limp mode on the highway, which caused a sudden loss of power and created a dangerous situation in traffic. The car also shakes, misfires, and loses power unexpectedly, which could lead to stalling or loss of control at highway speeds. I do not feel safe driving the car. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes. Multiple Hyundai dealerships have inspected the car. One confirmed low oil pressure and oil contamination at the sensor. Previous visits dismissed the oil warning and charged me for oil replacement instead of identifying the underlying defect. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? Yes. The vehicle has been inspected by Hyundai dealers multiple times. I also have two inspection reports from the same dealer just two weeks apart with contradictory findings the first showing no oil issue, the second confirming oil contamination and failed oil pressure. Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? Yes. The oil warning light and check engine light have both come on. The vehicle has gone into limp mode, and symptoms have included shaking, misfiring, rough idling, and loss of power. These issues began months ago and have continued despite repeated service visits.

NHTSA ODI 11686681

WHILE DRIVING ABOUT 45 MILES PER HOUR THE GAS ENGINE SHUT OFF AND THE ELECTRIC ENGINE LOST POWER, WERE ABLE TO COAST A FEW MILES UNDER LOW POWER UNDER ELECTRIC ENGINE AND THEN ENGINE SHUTDOWN COMPLETELY AND WOULD NOT START, HAD CAR TOLLED TO NEAREST MECHANIC, HE CONFIRMED ENINGE DAMAGED BY ROD BEARING FAILURE, HE TRIED TO GET A NEW ENGINE TO REPLACE THE DAMAGED ONE AND HYUNDAI TOLD HIM THEY COULD NOT SELL HIM AND ENGINE

NHTSA ODI 11682619

I am leasing a 2017 Hyundai Sonata from Car City in Michigan. In May 2025, the vehicle received a brand-new engine replacement due to previous problems. I picked the car up on [XXX], and on the same day, the vehicle began malfunctioning. It would not accelerate properly, jerked and stalled, and multiple warning lights — including the check engine light — came on immediately. This made the car unsafe to drive. I contacted the dealer, but they told me to wait until Monday to get it looked at, leaving me with a dangerous and unreliable car. The vehicle had already been in the shop for over two months for the engine issue, and I had only driven it for six months beforehand. I believe the repair or replacement engine is defective or was not properly installed. This creates a serious safety hazard. A car that stalls while driving puts everyone at risk. I am filing this complaint so this issue can be investigated and addressed if others are affected. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11678429

The engine in my 2017 Hyundai Sonata has been burning excessive amounts of engine oil over an extended period. The issue started approximately 10,000 miles ago but has worsened recently, requiring frequent oil top-offs between regular oil changes. The oil consumption is abnormal and not consistent with normal wear. This excessive oil burning poses a potential safety risk, including possible engine failure, stalling, or fire hazard due to low oil levels if not monitored carefully. The vehicle has not yet experienced a complete failure but the risk concerns me. The problem has been observed consistently during normal driving conditions. I have not yet had an official inspection or oil consumption test performed by a dealer, but I intend to request one. There have been no warning lights related to the oil burning issue, but the oil level drops rapidly and noticeably.

NHTSA ODI 11678234

Constant losing oil, constant changing of spark plugs, car shaking, can't pick up speed

NHTSA ODI 11677707

All documents are attached as it is many separate incidents that ended knock from motor and minutes later, a piston shooting through the engine block which is what made the car inoperable

NHTSA ODI 11673236

The check engine light light is on now giving code p200a I was driving and the center console shut off and the engine died I had to pull over and start the car again it started but the check engine light light is on now for a p200a I’ve looked it up and everything I can find says there is a recall but my car isn’t in it so what can I do I don’t want to cause a fire or an accident because my car messed up o. Me

NHTSA ODI 11652308

I have had many problems with my car since 1st day of purchase timing belt oilpans valve cover gasket burning excessive oil caliper brake hose last few events I have experienced my ABS light coming on in the car stop moving while am in traffic very dangerous I work for the hospice reserve one day while driving the car started shaking compulsive and the check engine light came on I was informed oil was leaking onto my spark plug and engine was going out I experienced extreme hot air inside the car coming out vents back firing etc my warranty in finical company seems to be ripping me off more concerned about money I have reported all these problems to them the past 13-14 months i was suppose to hear back from lisa warranty about this problem this past week no contact I reached out to Hyundai Corporation after visiting local dealership on Bedford automile a service rep by the name of aaron basically told me they cannot help me car will need a engine

NHTSA ODI 11622064

I have to add a quart of oil to car a day tul the motor blew

NHTSA ODI 11621170

The car is burning through oil at an excecated rate. This is a well-known issue with this make and model. The dealer said they fixed the problem, and they did not. This engine needs to be replaced. It was inspected by a mechanic not affiliated with Hyundai. Hyundai has refused to replace the engine. This should be covered by the 15 year/ 150,00 engine warranty. This engine could seize up at any time. It is a hazard to be driving. The driver is an 80-year woman. She needs help.

NHTSA ODI 11620373

I was driving the vehicle and it of no where the hybrid warming triangle comes up and I had to pull over. The car went in creep mode and then rpm and sped was capped.

NHTSA ODI 11612071

While driving on a highway at ~60 mph, the check engine light came on (plus other indicator lights) and the car immediately dropped to ~45 mph. ~20 seconds later, while trying to pull into a school parking lot, the hybrid system fault warning came on and the car dropped to ~5-10 mph and then became extremely difficult to control. The car was towed ~80 miles to my home dealership and it was diagnosed as a partially blocked EGR tube. ~1 month later, on the next longer drive I had to make (all other drives were short distances), ~70 miles into the drive, the car started making a knocking sound and then suffered the same failure under the same kind of conditions. This was diagnosed as a failed knock sensor. One week later I tried to drive it a long distance to see if the problem would happen again (but closer to home) and while traveling on an interstate highway the same issue occurred. This time it was diagnosed as oil in the wiring assembly for the just replaced knock sensor. The dealership tried to give me the car back but I demanded that they do a long test drive. It took 4 days to get them to do what I asked and then they had it break down on them in the same way. I'm not 3+ weeks after that and still don't have the car back (now they're planning to replace the EGR assembly and intake manifold). Each breakdown has thrown the P1326 trouble code but Hyundai refuses to admit that the issue may be the engine itself (related to the recall). It took until the 3rd breakdown and a lot of demands to get a loaner vehicle. I don't know if this is the known engine issue, something else or new but don't feel that Hyundai is taking it seriously. If nothing else, the programming that was added to put the car in safe mode and prevent fires is too aggressive and in each case has made the car undrivable in less than 1 mile. I have gotten lucky in all cases that a safe place to stop was nearby but it is not safe to drive in many areas due to lack of safe pull off location

NHTSA ODI 11585677

My son was driving the car, and completely out of nowhere it seized to have any compression and steering/accelerating became disabled. I have been given an estimate up to $7,000 for an engine rebuild due to this happening. I have reached out to Hyundai and they denied my claim due to car being out of warranty. This should have never happened when the car has been well maintained,even with the motor burning through oil faster than it should be, which I have always kept a close eye on. This car is defective and unsafe.

NHTSA ODI 11584184

Engine oil light or any warning lights and symbols never came on after Engine had burned out all the oil. Had oil changed and new oil filter installed and in less then a week it burned out 3 quarts, again with no low oil warning at all. Motor stalled at intersection and had to cool down, oil was again added and lower Engine knocking was present. Meanwhile had a mechanic inspect it and diagnostic done and lower bearings are knocking. Vehicle has had this issue for over 4 years and never mentioned to us until now after 100,000 miles. 2019 is when this oil burning issue began. Hyundai dealer serviced this several times and never mentioned the reason for the knocking other then it was low on oil. After breaking down in a busy intersection had to be pushed off road and waited for Engine to cool down to add oil and knocking continued.

NHTSA ODI 11574962

My 2017 Hyundai sonata burns oil rapidly, almost 400 miles it burns 5 quarts of oil. The engine stalls randomly and beings to mis fire. The car has stalled on me in the middle of the road with no check engine light or indicator that a problem is present. I have had to change spark plugs and coils far to offen and every time I have to pay the mechanical shop. There is a recall on the hybrids sonatas but not the gas ones. The dealer acknowledges that the car burns oil allot. Which I’ve been told it can lead to engine failure I have done everything possible. And I’ve spoke to other owners and I’m not alone. The vehicle hasn’t been inspected by others such as police. No warning lights appear

NHTSA ODI 11572715

I was traveling on [XXX] Baton Rouge La. and Gonzales La. at 70 mph when I lost power to my vehicle , an alarm sounded saying it was the Hybrid control system failure, putting my safety at risk as I had to maneuver off the interstate and onto the shoulder during heavy traffic . I called State Farm insurance to get my vehicle towed to Ralph Sellers Hyundai in Gonzales La. where it is being repaired. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11564410

While driving the vehicle on the highway, the check engine light began flashing and the car immediately lost almost all power. We had enough power to pull off of the highway off-ramp where the vehicle began jolting before stalling on a side road. We started the car back up and had just enough power to drive into the hospital parking lot next to the side road, where we had it towed to the Hyundai dealer across the highway. That Hyundai dealer identified the Intake Manifold Runner as the culprit via engine fault code P200A00. This Hyundai dealer was also concerned with oil consumption as the car's oil was low even though it had been maintained according to Hyundai standards. They did an oil consumption test, but argued that it was normal, while refusing to repair or replace the Intake Manifold Runner, & only cleaned the Intake Manifold Runner, for which they charged. They gave us the car back and it continued to consume oil to the point where the dipstick was reading below the low line. The car also continued to jolt and have low power. This same Hyundai dealer told us to add oil to the engine and have it towed to them, which we did. They then claimed the car had too much oil, blamed us for it, and continued to refuse to investigate the issue any further. They gave us the car back after a lot of confrontational back and forth on their part where they agreed to change the oil and do another oil consumption test at no charge. A few weeks later, the check engine light came back on, the car lost power, and we called the same dealer back. The dealer refused to help us, so we took it to another dealer who found the same P200A00 fault code and replaced the entire Intake Manifold Runner under warranty without any questions asked, and at no charge. When we were still dealing with the first Hyundai dealer, we opened a case on them through Hyundai corporate, but corporate did nothing and did not care about the issue. Hyundai Corporate and one of their dealers ignored 21-EM-008H.

NHTSA ODI 11547775

The car is consuming excessive amounts of oil. The engine has a knocking, tapping sound. Found out today the intake manifold is bad, which we all know is a very bad thing to go wrong. The engine has a very bad misfire. The car only has 53k miles. I own an 09 Sonata with 154k and I have never had a problem. This is why I continued with Hyundai. Also, the steering seems to tense up regularly. I am very worried about driving this vehicle. I have read hundreds of complaints regarding the excessive oil consumption. I feel you need to express the importance of these concerns to Hyundai

NHTSA ODI 11547426

Burning over a quart of oil every 500 miles.

NHTSA ODI 11545929

On 12/26/22, I was on a road trip and the car began vibrating violently on the PA turnpike. The car was losing power and would not accelerate. I was forced to stop on the highway with my kids in the car. Hyundai repaired the cylinders in the engine and then it began burning excessive oil, 1 quart ever 1000 miles. For months, I drove this car and as the oil got lower, the car hesitated while driving and ran very rough. On 7/4/23, transmission overheated and once again, car lost power on the road and left me stranded with my kids. Engine is burning excessive oil and causing other issues with car. Was not fixed when car died the first time and has now left me limping along and stranded twice. Car has been at shop since 7/5/23. Engine approved, but dealer can’t get parts. Hyundai won’t approve transmission until engine is replaced, leaving me to drive an unreliable car again when transmission and engine both have known issues. It’s unsafe to continually be stranded by a car that clearly has a bad engine. Would have been more cost effective for Hyundai to replace car at this point and still being given runaround by corporate.

NHTSA ODI 11538586