Hyundai Sonata engine failure problems

Filed Nov 2, 2026 · Engine · FL

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

Filed Oct 29, 2026 · Engine, Steering · FL

I am filing a formal safety complaint regarding severe vehicle instability, structural safety risks, and dealership workmanship negligence following a federal safety recall engine replacement. My vehicle received a new engine block under a federal campaign at a local dealership. Immediately upon picking up the vehicle, the front suspension developed a severe, heavy mechanical knocking and bumping noise over road surfaces under 20 mph, making the vehicle structurally unstable and hazardous to drive. To perform this engine swap, technicians were physically required to drop the front subframe framework and disconnect the lower suspension linkages and steering column components. The dealership is actively trying to deflect safety accountability for an assembly error. They issued a new estimate attempting to charge me over $3,200 to replace the entire front strut and rear shock assembly, claiming it is a 'pre-existing wear-and-tear' issue due to mileage. However, I hold the dealership's official Multi-Point Vehicle Inspection report from when the car was first dropped off for the engine failure three weeks prior. In that mandatory baseline safety report, their own technician thoroughly checked the under-carriage and officially marked my 'Shock Absorbers / Suspension' and 'Steering Gear Box / Linkage and Boots' as PASSED with green checkmarks. This objective paper trail proves the front chassis was tight, silent, and structurally safe before the repair. The safety hazard was introduced solely during the dealership's engine reassembly. The Service Manager explicitly refused to step out of his office to address this safety complaint, and the dealership released a compromised, structurally unsafe vehicle to a consumer. I request a formal federal safety investigation into this branch's safety compliance regarding recall implementation.

Filed Oct 28, 2026 · Brakes, Electrical · CO

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.

Filed Oct 26, 2026 · Engine · 180,000 miles · FL

The contact owns a 2017 Hyundai Sonata. The contact stated that while driving at 65 MPH, there was an abnormal sound coming from the vehicle with the check engine warning light illuminated. The vehicle was taken to an independent mechanic, where it was diagnosed with engine failure. The contact was informed that the engine was consuming oil. The contact referenced an unknown recall; however, the VIN was not under recall. The contact was informed to take the vehicle to the dealer for assistance. The failure mileage was approximately 180,000.

Filed Oct 18, 2026 · Engine · NJ

My 2011 Hyundai Sonata with the 2.4L Theta II GDI engine developed an engine failure at 99,928 miles. On XXX Hyundai’s dealer (McFarland Hyundai, [XXX]) ran Hyundai’s T3G connecting-rod-bearing test, and the engine returned NO PASS. Hyundai’s own test recorded the oil level as full. This engine family is the subject of Hyundai’s connecting-rod-bearing safety campaigns and its extended engine warranty. Hyundai declined the repair (#XXX) as “exceptional maintenance neglect,” although the oil and filter were changed about 730 miles before the failure, with two more documented oil changes in the prior 16 months. Connecting-rod-bearing failure in this engine can cause engine seizure or stalling while driving, which creates a crash risk. The vehicle is at the dealer and has not been repaired. I am reporting this so the federal safety agency has a record of a Theta II failure in a vehicle covered by these campaigns that was denied repair. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Oct 15, 2026 · Engine, Fuel system · NY

Summary of Event: This vehicle was brought to an authorized Hyundai dealership for a mandatory safety recall engine replacement under the Theta II Engine Recall Campaign. The dealership successfully installed a replacement engine provided by the manufacturer. However, the dealership and Hyundai Motor America are now refusing to return the vehicle to me in a functional, safe condition. Safety Hazard & Defect: The dealership states that the replacement engine shipped by Hyundai is mechanically and physically incompatible with the vehicle's original, factory-installed high-pressure fuel pump (HPFP). In an official written correspondence from a Hyundai Motor America Corporate Case Manager, Hyundai explicitly documented that: "dealership stated that it is not safe to drive the vehicle with old fuel pump." Despite acknowledging that the vehicle is now in an "unsafe to drive" condition due to the mismatched replacement parts provided by the manufacturer, Hyundai Corporate and the dealership are refusing to complete the safety recall remedy unless I pay $1,500 out-of-pocket for a new, compatible fuel pump.

Filed Oct 13, 2026 · Engine · FL

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)

Filed Oct 11, 2026 · Engine, Fuel system · TX

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

Filed Oct 7, 2026 · Engine · NY

2013 Sonata 2.4 81,953 mi, seized on highway with fresh oil change 1 week prior, loss of power, steering/braking. Happened on George Washington Bridge (NY/NJ) with near collision. Asssited by Police to move vehicle out of highway. Inspected by dealer (Paramus Hyundai) and confirmed loss of power due to engine problem. Dealer denied warranty for poor maintenance despite receipt showing recent maintenance. This vehicle is covered under life warranty by Hyundai for manufacture defective engine, yet they denying engine replacement. The engine problem is a serious safety risk.

Filed Oct 6, 2026 · Engine · 60,436 miles · MI

The contact owns a 2016 Hyundai Sonata. While the contact's daughter was driving 55 MPH, the engine seized. The contact stated that the failure had occurred while the contact's two minor grandchildren were inside the vehicle during the failure. The vehicle was towed to an independent mechanic. The vehicle was later towed to the dealer where it was diagnosed with engine failure. The contact was informed that the engine needed to be replaced. The manufacturer was contacted, and a case was filed. The contact was informed about the eligibility for the extended warranty under Campaign 953. The contact was informed that the repair was not covered under the extended warranty because the Campaign 953 was not completed. The failure mileage was approximately 60,436.