I am writing to formally report a serious and potentially dangerous safety issue involving my 2015 Hyundai Sonata. At approximately 93,000 miles, my vehicle experienced a complete engine failure, which resulted in Hyundai replacing the engine. Unfortunately, I am now experiencing another serious mechanical or electrical malfunction. While I am driving, my vehicle unexpectedly shuts off completely. When this happens, I cannot restart it immediately. I must wait approximately two to five minutes before the vehicle will restart. This situation is extremely concerning because it exposes me, my passengers, and other motorists to a significant safety risk. An unexpected shutdown while traveling on a public roadway could result in a serious accident. Given the vehicle's previous engine failure and Hyundai's subsequent engine replacement, I am requesting a thorough investigation into whether the current malfunction is connected to the replacement engine, its associated components, or another underlying defect. Specifically, I am requesting: A comprehensive diagnostic inspection to identify the cause of the unexpected shutdowns and delayed restarts. A review of the vehicle's previous engine replacement and repair history. Verification of all applicable warranties, extended engine coverage, recalls, and service campaigns. Written documentation of the diagnostic findings and the recommended corrective action. Consideration of full warranty coverage or goodwill assistance for repairs associated with the previous engine replacement or any covered defect. Assistance with safe transportation or towing, given the risk of driving the vehicle in its current condition. I have a dealership service visit scheduled for Saturday, November 7, 2026, and I am notifying Hyundai in advance to ensure that this serious safety concern is formally documented. I respectfully request written acknowledgment of this complaint, a case number, and confirmation that the dealership will inve
2015 Hyundai Sonata engine problems
650 complaints (56% of all complaints for this car). Typical mileage when it fails: 66,369. 4 crashes reported.
- owner complaints
- 650
- of this car's complaints
- 56%
- typical mileage
- 66,369
- crashes
- 4
- recalls
- 0
Which part fails
- Engine: engine control module (ecu/ECM)1
- Cooling system1
At what mileage
Complaints by mileage at the time of the problem.
Hyundai Sonata engine problems in other years
Specific symptoms reported on the 2015 Hyundai Sonata engine
Phrases found in the owners' own descriptions, so one complaint can mention several symptoms.
Check engine light 216Engine failure 166Stalling 160Knocking 117Loss of power 94Oil consumption 85Won't start 31Misfire 25Overheating 12
Related recalls
No recalls on record for this model year.
Related investigations
Loss of Motive Power
the federal safety agency 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. The Petitioners cited examples of complaints indicating that the subject vehicles were experiencing rapid loss of engine oil due to oil drain plug back outs, resulting in loss of motive power and/or catastrophic engine damage. Additional complaints were provided which alleged that the oil drain pans lack sufficient structural integrity and are susceptible to cracking. The petition itself can be reviewed at under ODI number 11481745. On September 12, 2022, the Office of Defects Investigation (ODI) opened Defect Petition (DP22-003) to evaluate the Petitionersâ request. The Petitioners have provided additional complaints within four supplemental letters dated January 31, 2023, March 21, 2023, May 23, 2023, and August 4, 2023. ODIâs evaluation included the review and analysis of the complaints and supporting information submitted by the Petitioners, as well as additional complaints submitted directly to the federal safety agency which referenced either the oil drain plug or a crack in the oil pan. After reviewing the available data, ODI has not identified evidence that would support opening a defect investigation into the oil drain pan assemblies of the subject vehicles. Based on a review of the available information, a loss of motive power resulting from an oil drain plug back out has not occurred between the initial sale of a vehicle and the completion of its first oil change. If during an oil change service, a technician fails to remove the existing drain plug gasket before installing a new gasket, it is likely that a proper seal between the drain plug and the oil pan will not be made. An improper seal between the drain plug and oil pan could lead to the backing out on the drain plug, resulting in the sudden loss of oil while driving. Additionally, the provided examples of oil pan cracks were localized to the immediate vicinity of the oil drain plug and/or appeared to be the result of direct-contact with a tool during servicing. Â There is no information to support that a vehicle-based defect exists relating to the oil pan assembly, and instead the documented incidents are related to the failure to follow the proper maintenance procedures during oil change service. In October 2023, Hyundai published a Technical Service Bulletin (TSB) that provided detailed instructions for oil change service on its gasoline powered vehicles, specifically highlighting the need to remove and replace the existing drain plug gasket prior to reinstalling the drain plug. After a thorough review of the material submitted by the petitioner, the information already in the federal safety agency's possession, and the potential risks to motor vehicle safety implicated by the petitioners' allegations, the federal safety agency does not believe that a formal investigation is warranted. Therefore, the petition is denied. A Federal Register Notice (FRN) further detailing the federal safety agencyâs reasons for denial of the petition will be published. The reference numbers for the complaints to the federal safety agency cited by the petitioner can be found in the petition submission documents in the public file for DP22-003. To review those complaints and the additional complaints ODI added to its evaluation which are cited in the Closing Resume ODI Report Identification Number document, go to
DP22003
Engine Fires
On March 29, 2019, the Office of Defects Investigation (ODI) opened two Preliminary Evaluations (PE19-003 on Hyundai and PE19-004 on Kia) to broadly investigate incidents of non-crash fires (regardless of origin or operational status of the vehicle) on various model year Hyundai and Kia vehicles. During the PE investigations, Hyundai and Kia issued several recalls to address vehicle fires, including those due to engine failures involving various engine types. The remedies for the engine failure recalls typically involve engine inspection (to detect existing damage), and if necessary, engine replacement. Additionally, both manufacturers have been installing an engine control software modification known as Knock Sensor Detection Software (KSDS) which is intended to detect impending engine failure, alert the driver, and limit engine power (to lessen likelihood of engine failure).KSDS is being installed under recalls and non-safety field actions, and both companies have extended limited engine warranties (see recall files). On December 22, 2021, ODI upgraded PE19-003 and PE19-004 to this Engineering Analysis (EA21-003, covering both Hyundai and Kia) to evaluate the scope of the prior recalls related to engine failures/fires and the efficacy of the recall remedies for the recalls, as well as the long-term viability of related programs and non-safety field actions being conducted by Hyundai and Kia. The former issue involved approximately 550,000 MY 2013 Hyundai Elantra, MY 2011 Kia Sorento, and MY 2012-2015 Kia Rio. The latter issue involved approximately 2.5 million recalled vehicles, which have been identified as displaying potential remedy concerns: Hyundai recalls 15V‑568, 17V‑226, 20V‑746, and 21V‑727; and Kia recalls 17V‑224, 19V‑120, 20V‑750, and 21V‑844. Regarding the recall scope issue, among all of the scope vehicles identified at EA opening, ODI found only the MY 2011 Kia Sorento vehicles equipped with both the Theta II 2.4L 4-cylinder Multi-Point Injection (MPI) and the Lambda II 3.5L 6-cylinder MPI engines experienced relatively high rates of reported fires. In December 2023, Kia issued recall 23V‑877 that will cover about 80,000 MY 2011 Kia Sorento vehicles equipped with the Theta II 2.4L MPI engines.  The remedy will involve an inspection, and if necessary, a replacement of the engine, as well as the installation of KSDS.  It should be noted that in 2021 these vehicles were included in a KSDS product improvement campaign with warranty extension. For the MY 2011 Sorento vehicles equipped with the Lambda II 3.5L engines, ODI believes that future engine failures/fires involving these vehicles will likely be due to a lax in adhering to the proper or scheduled engine maintenance (regular engine oil changes), rather than a design or manufacturing engine issue. Regarding the issue of the efficacy of the recall remedies, ODI found the majority of the recalled Hyundai and Kia vehicles, by model, experienced lower reported fire rates after the remedies were applied. Furthermore, ODI found that for most vehicles that did not receive the recall remedies, by model, experienced relatively high fire rates. To address this problem, Hyundai informed ODI in December 2023, that it will renotify all of its owners covered by the Hyundai recalls of engine failures/fires every 8 months for the next 3 years. In December 2023, Kia stated that it will renotify the majority of its owners every 8 months for the next 3 years.Several previously recalled Kia models are excluded from the renotification due to their lower reported rates of engine fires. Overall, the renotification actions will help to increase the recall completion rates, thus reduce the frequency of engine fires in the future. In view of the recall action being taken by Kia and renotification actions being taken by both Kia and Hyundai, ODI is closing this Engineering Analysis. Also, both companies have been released from the 2020-iniated Consent Orders (Kia since November 2022 and Hyundai since November 2023). The agency reserves the right to take additional action if warranted by future circumstances. To review the reports cited in the Closing Resume ODI Report Identification Number document, go to
EA21003
What 2015 Hyundai Sonata owners say
Most recent owner complaints, unedited.
On Wednesday, October 21, 2026, our 2015 Hyundai Sonata with the 2.4L Theta II GDI engine suffered a sudden, complete engine seizure while traveling about 75 mph on I-25 Southbound near Castle Rock, CO. A family member was driving. Warning lights across the car began flashing, the engine made a loud grinding noise, and the brakes stopped working. Over a long distance, the driver was able to get the car onto the shoulder and bring it to a stop, then engage the parking brake. There was no collision and no injuries, only because traffic was light. The car was towed to a repair shop, then transferred to a second shop, which determined the engine had seized and requires full replacement. This vehicle is covered by Hyundai's Theta II GDI engine campaigns for connecting rod bearing failure. On October 26, 2026, Hyundai told us the Knock Sensor Detection System software update (Campaign 953) was never completed on this vehicle and declined coverage. Neither we nor the prior owners, who are family members, recall receiving any notice of this campaign. All previous check engine lights were diagnosed and repaired at independent shops, including an intake manifold replacement in April 2024, and no shop ever identified an open engine campaign. A full engine seizure at highway speed, combined with the loss of braking, creates a serious crash risk for the driver and surrounding traffic.
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.
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 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 the federal safety agency 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.
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.
Questions about the 2015 Hyundai Sonata engine
Does the 2015 Hyundai Sonata have engine problems?
Owners have filed 650 complaints about the engine of the 2015 Hyundai Sonata, 56% of all its complaints, more than any other problem.
At what mileage do 2015 Hyundai Sonata engine problems start?
The typical (median) mileage in owner complaints is 66,369 miles.
Was there a recall on the 2015 Hyundai Sonata engine?
There is no recall for this problem on this model year.
What year does the Hyundai Sonata have bad engine?
The Hyundai Sonata model years with the most engine complaints are 2011 (1,012 complaints), 2013 (778 complaints) and 2015 (650 complaints).
Other 2015 Hyundai Sonata problems
Electrical 168Transmission 135Fuel system 87Brakes 80Steering 74Acceleration 61Body 52Lights 38Visibility 30Driver assistance 29Airbags 25Seat belts 21Suspension 17Wheels 15Seats 14Tires 4Locks 2
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