Hyundai Sonata stalling problems

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 · Brakes, Engine · KY

Vehicle experienced intermittent, severe powertrain defect resulting in a critical safety hazard. Between 30K and 36K miles, the vehicle underwent 3 violent highway deceleration episodes. During these events, the engine began shaking, escalating to violent shaking; with deceleration and coming to a stop, it would shake, then sputter as if it would die. Coming to a complete stop, a total stall was prevented only by the ECM forcing a limp mode lock at 1200 RPMs. When Auto Hold was engaged at this point and my foot was removed from the brake pedal, the mechanical surge caused the vehicle to unexpectedly lurch forward, fighting against and nearly overriding the factory Auto Hold braking safety feature before finally holding. Luckily, no pedestrian was walking in front of my car when this occurred. No check engine light (CEL) or dashboard warning ever illuminated. This safety compromise is directly tied to an ineffective or adjacent remedy involving Service Campaign 9B1 (Opcode 40D219R0) and Safety Recall 286. Under this Opcode, a factory software flash deleted the standard OBD-II trouble code P0451and substituted it with a manufacturer-specific shadow code P14EE00. This software manipulation suppressed universal emission/pressure sensor faults, masking a volatile physical defect within the high pressure fuel delivery and ignition systems. Dealer diagnostics on a running, compromised engine flagged an improper fuel injector pulse and subsequently a failing Cylinder 3 ignition coil. All four injectors were replaced but only one coil, leaving 3 non-updated , factory defective coils in the engine. The vehicle remains an ongoing highway stalling and brake-override hazard due to an incomplete field remedy of a recall-adjacent system. I've filed a Hyundai Complaint with assigned case number 43394228 regarding Safety Recall 286. (Two episodes of the attempted Auto Hold override occurred - first 09/09/2026 and second 09/29/2026.)

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 Sep 15, 2026 · Engine · IN

I am concerned that the engine may seize or stall without warning while driving, creating a risk of crash, injury, or death. The Theta II engine defect is known to cause engine seizure, stalling, and fire. Hyundai has denied warranty coverage based on mileage and second-owner status — both of which are explicitly prohibited as denial grounds under the Settlement — leaving me driving an unsafe vehicle.

Filed Sep 4, 2026 · Engine · UT

The vehicle suffered a sudden, catastrophic internal mechanical engine failure out of nowhere without any warning lights or previous symptoms. An inspection of the engine cylinder revealed a physical hole blown through the top of the Cylinder 2 piston, causing immediate and complete loss of engine compression. This sudden structural failure caused the vehicle to completely lose all propulsion and stall unexpectedly while in operation, creating an immediate, severe safety hazard on the road.This vehicle features Hyundai's 2.4L Theta II Gasoline Direct Injection (GDI) engine, a family with a well-documented history of manufacturing defects, severe oil consumption, and catastrophic internal structural failures. Because this failure occurred instantly and without a progressive warning, it put occupants at risk of a severe rear-end collision or stranding in an unsafe traffic pattern. I am filing this safety report because the catastrophic destruction of the internal engine components presents a persistent and dangerous hazard to public safety.

Filed Sep 4, 2026 · Fuel system · TX

My car stalls while driving and then I try to restart it but nothing happens. After reading online about the fuel pump issues and extended warranty related to the fuel pump I took the car in for repair. My car has 75,000 miles and the extended repair on this is for 150,000 miles/15 years. The dealer is refusing the repair because my car has a branded/ theft title. The car wasn't damaged just stolen. This is creating a serious safety concern and should be repaired by the dealer. Thank you for your time.

Filed Aug 18, 2026 · Engine · CA

The vehicle suffered an internal connecting rod bearing failure, a known manufacturing defect affecting the Theta II GDI engine. The failure was explicitly diagnosed via the manufacturer - specific OBD-II fault code p1326 Knock Sensor Detector System. This defect causes sudden engine stalling poses an immediate risk of catastrophic engine failure or fire while driving. Hyundai Motor America has denied financial reimbursement for the required engine repair because the work was completed by an independent shop and third-party arbitration deadline (BBB Auto Line) communicated to me. The manufacturer is actively refusing to remedy an acknowledged safety defect.

Filed Aug 18, 2026 · Electrical · NJ

The AC/heating blower motor circuit on my 2020 Hyundai Sonata failed intermittently due to extreme electrical resistance overheating and melting the terminal pins inside the engine fuse box. I took it to the dealership and they inspected it said it was out of warranty but it needed part number 18980-09910-FFF and wiring kit 91300L1000-FF to repair at a cost of 780.00 including parts, tax, and labor. This matches the severe design defect acknowledged in Hyundai TSB #25-EE-002H or alternative TSB-24-EEOO-1H. I filed case number 43138757 with Hyundai corporate. For now this just affects my air conditioning. However, the root failure is a known design defect that presents a severe vehicle fire hazard and potential loss of windshield defrosting capability, lights, etc. if the whole electrical system should fail. As you should know the engine bay fuse box (which currently has melted parts) is the "brain" for the car's electrical distribution. It doesn't just power my AC fan; it holds the fuses and relays for the cars fuel pump, engine control module (ECM), headlights, and electronic power steering. If left unfixed and over time as the plastic melts, copper wires will cross and touch each other, causing a massive short circuit. My engine could suddenly cut out and stall while I am traveling at 70 mph on the highway, instantly killing my power steering and power brakes and putting me in extreme danger. Again not to mention the fire hazard this situation is likely to cause. This should be addressed via a mandatory safety recall, so that I don’t have to pay for a known engineering design defect and in case the TBS bulletin fails or further unknown damage has already occurred.

Filed Aug 16, 2026 · Engine, Transmission · TX

I recently had the 9C2 Emissions recall update performed on my car, and since the update my car drives like total garbage after a cold start. It hesitates to accelerate, it bucks when trying to accelerate, and it’s to the point the engine is about to stall. I took it back to the Hyundai dealership and they said they are aware of the issue, but there is no fix from Hyundai at this time. This is a major safety concern, as the car barely wants to accelerate after a cold start. Please have Hyundai fix this safety issue.

Filed Aug 13, 2026 · Engine · NJ

On January 26, 2026, my 2019 Hyundai Sonata SEL suddenly became inoperable overnight. The vehicle had been operating normally with no warning signs—no check-engine or oil-pressure light, abnormal engine noise, overheating, loss of power, or other indication of an impending failure. The following morning, the engine would not start. The vehicle was towed to an independent mechanic on January 28, 2026, who determined that the engine was locked/seized. On February 11, 2026, it was towed to Wayne Hyundai for further diagnosis. The vehicle had only 51,533 miles and had received Hyundai’s Knock Sensor Detection System (KSDS) update. Hyundai denied warranty coverage, citing engine sludge, despite my providing a complete service history after resubmiting the missing receipts I had previously misplaced. My primary concern is safety, not the warranty dispute. A sudden engine seizure without warning could cause an unexpected loss of propulsion or create a dangerous situation if the engine fails while the vehicle is being driven. This concerns me because Hyundai Theta II engines have previously been associated with engine seizure and stalling, including issues addressed through The Hyundai Theta II Engine Settlement: and subsequent litigation involving certain 2019 Sonata vehicles. I respectfully request that the federal safety agency investigate whether a continuing or insufficiently addressed engine defect exists in affected 2019 Hyundai Sonata vehicles, particularly sudden engine seizure/no-start failures occurring without warning. I also ask the federal safety agency to examine whether existing recalls, campaigns, software updates, warranty extensions, and other remedies adequately protect owners when an engine fails suddenly before the KSDS system provides a warning.