2015 Hyundai Sonata

A franchise dealership performed a federally mandated safety recall service (ECM Software Update) and a knock sensor replacement on this 2015 Hyundai Sonata 2.0L Turbo. To perform these specific repairs, the technician had to work directly around the intake and turbocharger assembly workspace. Immediately after picking up the vehicle, it suffered a sudden and dangerous loss of power and refused to accelerate normally on the highway, creating a severe traffic hazard. Upon an immediate emergency inspection by the same service center 5 days later, the dealership documented in writing that the turbocharger intercooler hose clamps were completely off/unfastened. Because the technician left the clamps disconnected, the turbo lost sealed pressure, failed completely, and began dumping high-pressure engine oil backward through the air filter intake box. The service center is now refusing to take responsibility for the mechanical safety failure directly caused by their technician's recall repair negligence.

The contact owns a 2015 Hyundai Sonata. The contact stated that while driving at 20 MPH, the driver-side windshield wiper failed to function properly. The vehicle was taken to an independent mechanic, who determined that the wiper blade was not making proper contact with the windshield due to a bent driver-side windshield wiper arm. The dealer was contacted and confirmed that no recall coverage applied to the failure. The contact associated the failure with NHTSA Campaign Number: 23V180000 (Visibility/Wiper). The contact notified the Hyundai manufacturer of the issue by phone. The failure mileage was approximately 26,400.

Hyundai Motor America is explicitly refusing to honor the mandatory safety recall and lifetime warranty extension for a catastrophic rod bearing failure on my 2015 Hyundai Sonata (VIN [XXX]). The engine suffered a sudden internal connecting rod bearing seizure while operating, causing a complete loss of motive power and creating an immediate hazard. Hyundai Corporate Escalations issued a blanket denial solely because the vehicle carries a rebuilt title. However, the vehicle's official Hyundai portal confirms that Service Campaign 953 (the Knock Sensor Detection System software update) was successfully completed on XXX. The engine failure matches the exact factory manufacturing defect (internal oil starvation from manufacturing debris) that is the subject of the In re: Hyundai and Kia Engine Litigation. The external collision history that led to a structural/rebuilt brand has absolutely zero mechanical correlation to a sealed, internal crankshaft block defect. Hyundai is acting in bad faith by using an unrelated title status to evade a federal safety recall mandate and escape liability for a dangerous, stalling powertrain defect. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I received a notice from Hyundai that there was a Service Campaign 9C2 for my car. My car was running fine but I took it to Jones Hyundai in Belair MD for oil change and the Service Campaign. After this work was done my car lost driveability, poor throttle response and transmission searching for correct gear. I notified Hyundai about my concerns and they replied they opened a case number. Corporate advice so far has been to let the car warm before driving, which has been marginaly helpful. It is hard to merge with high speed traffic because of poor throttle response and transmission searching for correct gear, I have had some close calls. I think cold weather will increase this problem.

I am filing this complaint regarding transmission and drivability problems with my 2015 Hyundai Sonata 2.4L following Hyundai Campaign 9C-2. My vehicle was running and driving perfectly before this update. I have always maintained it on time, followed proper maintenance schedules, and have records documenting its maintenance history. I never experienced these transmission issues before the update. The problems began immediately after the campaign was performed. In fact, I noticed the abnormal shifting before I even left the dealership after picking up my vehicle. Since the update, the vehicle has experienced poor and abnormal shifting behavior. I contacted the dealership to report the problem and also filed a complaint directly with Hyundai Corporate. I was told that Hyundai is aware of the issue, yet my complaint remains unresolved. I also located a document online indicating that Hyundai is aware of this problem. Additionally, I have seen numerous reports from other Hyundai owners describing similar transmission problems after receiving this same update. My vehicle has approximately 82,000 miles. The engine was replaced approximately one year before this complaint. Given the vehicle's excellent operation before the update, my documented maintenance history, and the immediate onset of the problems at the dealership, I am seriously concerned that Campaign 9C-2 caused or contributed to these transmission issues. I am requesting that NHTSA investigate whether this software update causes or worsens transmission shifting problems in affected Hyundai vehicles. Hyundai's awareness of the reported issue and the apparent number of similar owner complaints make this especially concerning. I believe this issue deserves investigation to determine its cause, assess any potential safety risks, and establish whether corrective action

Ever since the 9C2 software update was completed on 94/26, the car is experiencing hesitations not only in the first few minutes of driving but after the engine is hot. It was driving perfectly before this update.

On May 28, 2026, the panoramic sunroof on my 2015 Hyundai Sonata became off track while I was driving. I could not get the sunroof back into its proper position because it was off track. I continued driving, and while I was traveling on the highway, the sunroof panel detached from the vehicle and flew down the highway. This created a serious safety hazard to me and other motorists. I was not the original owner and did not know the vehicle was subject to a recall. After the incident, I researched the vehicle and discovered Hyundai's Sonata Panoramic Sunroof Recall, Campaign 152. Hyundai's official website states that my vehicle is affected by the recall. Hyundai's recall description states that the wind deflector can interfere with the movable sunroof panel and, in some cases, cause the panel to detach from its mounting tabs. It specifically warns that if the panel detaches while the vehicle is in motion, it could become an obstacle to other drivers and increase the risk of a crash. This is what happened to me. After discovering the recall, I took the vehicle to a Hyundai dealership to have the recall addressed, but the dealership refused to perform the recall repair. Hyundai's website states that the dealer will repair the wind deflector anchor plate at no charge. I'm asking NHTSA to determine the appropriate remedy when the recalled condition actually occured and resulted in the sunroof panel detaching while the vehicle was in motion.

am seeking assistance regarding a sudden and unexpected engine failure with my vehicle. The Sonata only had approximately 80,000 miles on it when the engine failed. Prior to this happening, I had never experienced any problems with the vehicle. There were no warning lights or other indications that there was an issue with the engine, and the vehicle had passed inspection. The engine failure happened completely out of the blue. I have also kept up with the vehicle’s maintenance, including regular oil changes. I recently replaced the battery and tires as well. Hyundai previously denied my claim, stating that the vehicle’s salvage title was the reason for the denial. However, I would like the circumstances of the engine failure and my maintenance history to be fully considered. The vehicle had relatively low mileage, was maintained, passed inspection, and showed no warning signs before the engine suddenly failed. I can provide maintenance records, receipts, inspection records, photographs, repair records, and any other documentation needed to support my claim.

"I am filing a complaint regarding severe vehicle jerking, engine surging, and rough transmission shifting immediately following the completion of Hyundai Service Campaign 9C2 (TSB 26-01-013H-1) on my 2015 Hyundai Sonata. The vehicle exhibits dangerous hesitation and lurching during cold starts. This behavior creates a traffic hazard when pulling out of driveways or into intersections during the first 3 minutes of operation. The manufacturer has acknowledged this cold-start defect in an internal 'Drivability Information' memo but has not provided a permanent remedy to repair the software logic."

After receiving the Hyundai Service Campaign 9C2 update on my 2015 Hyundai Sonata on XXX, I have started having jerky acceleration when the car is first started and am driving. Also, while driving at highway speed (65 mph)) and I take my foot off the accelerator to coast, the engine RPM drops suddenly, anywhere from 250 rpm to 750 rpm, then recovers abruptly to where it was at prior to the drop (typically around 2000 rpm). The engine rpm also drops while driving at slower speeds and recovers but is not as noticeable as it is at highway speeds. It was not doing this prior to the Service Campaign. There are no check engine lights or pending codes. I brought it back to the Hyundai dealer and discussed the issue with them on XXX. They acknowledged it was likely due to the Service Campaign and they did not want to keep the car to look at it and said no damage was being done and it was safe to drive. They said a fix was in the works but did not know how long until it was released and I should receive information in the mail on it. Video link [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

In March 2026 Hyundai did an emissions update Campaign 9C2. Since that update my 2015 Hyundai Sonata SE has run rough and shifted hard. Hyundai stopped doing the update in May 2026. Hyundai has not provided any update to fix the problem they created. I am worried the update is damaging the motor and transmission of a car that was running just fine prior to the update.

The engine failed due to the known recall defect, dealer confirmed loss of compression in cylinders 2 & 4. I am a federal employee stationed overseas on official duty orders, and Hyundai Motor America is delaying safety recall remedies and buyback negotiations since June 9th.

Engine locked up, crank bearing failure, found out there is known failures with this problem and Hyundai had a class action suit against them in the past and issued lifetime warranty for this engine due to this problem. Took car to local dealer, Clay Cooley in Sherman TX, they have been great but Hyundai corporate has denied the claim stating lack of maintenance records. Car has 175,000 miles on it, I have only owned it for about 5-6,000 miles. I have changed the oil in it twice myself I was able to prove one of those with a receipt but I don't have the other receipt and have been unable to get it. The dealer has records of oil changes up to 150k miles then I was able to find additional proof of other oil changes through car fax at smaller lube shops. The previous owner before me changed their own oil also and did not keep receipts I reached out to them with no luck. Ultimately there is only about a 10k mile gap of unprovable maintenance, this engine model has a known issue, it did not make it to 175k miles without proper maintenance, I can't control what previous owners did with their receipts but lifetime warranty should be lifetime not only if you can prove every detail from people you can't control.

I bought this car new in 2015, when I was at 97000 miles they had to replace the motor and turbo, I am now at 155844 and they are telling me that basically all 4 cylinders have low compression, cylinder 3 is the worst. They are telling me that this car has to have a new motor. I have not done anything to this vehicle to cause no compression. They want me to pay around 8800.00 to get this fixed.

Issue- fuel pump/supply line causing fuel to leak and fuel smell around the outside of the car. This can cause a major fire, explosion, death for myself and others around me. Problem has been confirmed by auto repair shop. No warning messages on car dash board, just strong smell of gas. Replaced gas cap and smell is still there.

Brake lights not working properly.

The contact owns a 2015 Hyundai Sonata. The contact stated that while driving on several occasions at various speeds, the vehicle lost power, and the check engine warning light was illuminated. The vehicle was taken to a dealer where it was diagnosed that the engine had failed and needed to be replaced. The vehicle was repaired, but the failure reoccurred within a year. The vehicle was taken back to the same dealer where it was diagnosed and determined that a software update was needed. The vehicle was repaired, but the failure persisted. The vehicle was then taken back to the same dealer, and there was oil on the pistons and a tune-up was needed. The vehicle was repaired, but the failure persisted. The vehicle was taken back to the dealer, where it was advised that an oil consumption test could not be provided until the pistons had failed. The manufacturer was notified of the failure, and a complaint was filed. The failure mileage was approximately 88,000.

My Hyundai Sonata engine stalled out while driving on the highway. I had it towed to a dealership with the hope they would fix the issue because it was supposed to be covered under warranty from a recall. The dealership said the engine replacement would be covered as long as they got approval from Hyundai. Hyundai apparently only asked that specific dealership for the service records that they had, didn’t even reach out to me or try to find any other service records on the vehicle and denied the claim for “neglect of maintenance” because that dealership only had records from 0-90,000 miles. The dealership got back to me and told me the news and I told them that I will get all service records from 0 miles to current. I got all those records together and sent them to the dealer. A week later they called and said Hyundai was again going to deny my request because of the same “neglect of maintenance” which isn’t true based on the records I have and they have. I have driven the vehicle less than 10,000 miles and there has been nothing wrong with it. No check engine lights ever and regular oil changes.

Vehicle: 2015 Hyundai Sonata VIN: [XXX] Mileage: ~85,000 Description of the Problem: While driving, the vehicle suddenly began producing thick smoke from under the hood without warning. I safely maneuvered to the shoulder to avoid an accident. The engine subsequently seized completely and became inoperable. My mechanic diagnosed this as a known internal manufacturing defect in the Theta II engine (connecting rod bearing failure), a widely documented issue for this model and production year. Oil and coolant levels were confirmed normal with no leaks, ruling out maintenance neglect. I initially paid for an unnecessary starter replacement before this diagnosis was confirmed. This is a serious safety hazard that could cause loss of engine power and control while driving, posing a risk to myself and other drivers on the road. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Since the 9C2 update on June 24, 2026, my vehicle has not driven the same. I'm experiencing clunky or harsh gear changes at low speeds, especially during stop-and-go driving. When I slow down and then accelerate again, the vehicle sputters or hesitates before responding. While driving at lower speeds, I also feel intermittent skips or small surges, almost like bubbles or brief misfires. These symptoms were not present before the 9C2 update, and they have noticeably affected the drivability of the vehicle. It was suggested the transmission needed time to "relearn" driving patterns, but it has been several weeks with no change