2012 Hyundai Sonata Engine Problems

The contact owns a 2012 Hyundai Sonata. The contact stated that while driving at 30 MPH, the check engine warning light illuminated, the engine started knocking, and smoke emitted from under the hood. The contact decelerated to approximately 15 MPH and drove to her nearby residence. Upon inspection, the contact observed green fluid under the hood. The vehicle was towed to an independent mechanic, where it was diagnosed that the engine had failed and the head gasket was blown. The mechanic informed the contact that the engine needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 100,000.

NHTSA ID

11754020

Incident

Jul 30, 2026

Mileage

100,000 mi

Vehicle engine caught fire in April 2026! Tow company sold for parts without my permission! Immediately after gaining possession of my car. I didn't have comprehensive insurance, only basic. I had a brain bleed stroke Nov. 2022 and this is causing stress, setbacks. No attorneys want to take the case because there was no injuries! I jumped out in time. THANK GOD!

NHTSA ID

11753672

Incident

Apr 10, 2026

Diagnosed 07/20/2026 with catastrophic oil ring failure requiring engine replacement. Engine can stall due to oil degradation/absence of causing uncontrolled vehicle handling and fire. This would put myself and others at risk. It has been diagnosed at dealership. Complaint Narrative: The subject vehicle is experiencing its third total engine failure due to an inherent manufacturing and design defect, presenting a severe and repeating highway safety hazard. The original factory engine failed catastrophically in 2015 at 116,440 miles and was replaced under NHTSA Recall 15V-568. The second engine failed in 2021 at 244,710 miles and was replaced under NHTSA Recall 17V-226. The third engine (the second replacement) has now failed prematurely at 334,935 chassis miles, lasting a mere 90,225 miles. An authorized Hyundai dealership diagnosed a total failure of the oil control rings. This mechanical defect allows engine oil to bypass the pistons directly into the combustion chambers. This causes severe, rapid oil consumption, spark plug fouling, engine stalling, and total loss of motive power at highway speeds without prior dashboard warning illumination. The manufacturer is failing to provide safe, durable remedies for its federally mandated safety recalls (see warranty info Magnuson-Moss Warranty Act (15 U.S.C. § 2301 et seq./ Breach of Implied Warranty of Merchantability). Instead, they are installing subsequent replacement powerplants that suffer from the exact same structural vulnerabilities and component lifecycle failures. This creates a continuous risk of sudden engine seizure and traffic collisions for consumers.

NHTSA ID

11753470

Incident

Jul 20, 2026

See attached document for complaint.

NHTSA ID

11752062

Incident

May 13, 2026

As I was merging onto the interstate I put my foot on the gas pedal to give it a little more gas then usual to get pulled out and all of a sudden all the lights on the dash board illuminated and it slowly lost all power I was able to move it out of the road ... There was no loud ,knocking or ticking noises prior to this happening there was no type of any kind of warning .. my car is the push start button so after the car died completely I hit the push button and all the lights on the dash came on the radio worked and everything else seemed to be working it was when I went to put my foot on the brake to start it it would do nothing it would not start at all .. I was still able to put it in neutral even after the incident happened . I had it towed t Hyundai of Bristol to have it inspected well they did verifi that the engine was locked up but failed to give me any information on the test they ran or how they keep it was locked up and what locked it up so then they have my car over a week and they tell me I need a new engine but then contact me to tell ke that HMA refused to replace the engine on warranty and I had the campaign 953 completed the knox sensor thing before my car broke down so then I had to pay for towing once again out of my pocket to go pick the car from their dealership so when I got there to get my car the service was not that great and my car was in a mess very uncalled for the battery to the car was completely dead with that being said we had to use another battery to just get it turned on to even put it in neutral well then fuel started spraying from the fuel line , the engine cover was left off right along with engine mount was taken off and they even took the belt off there were bolts laying all over my hood of my car and I'm pretty sure we lost a few transporting the car back ..their service they provided was not business/professional behavior and very disrespectful at that .. returning my car in that condition was very unnecessary

NHTSA ID

11750478

Incident

May 13, 2026

Around the end of May 2026, my vehicle stalled without warning while traveling at highway speed. The engine light and EPS warning light illuminated simultaneously. The engine cranks but will not start. The vehicle was towed to a Hyundai dealership on June 15, 2026 where the engine failure was confirmed. My safety was directly at risk. The vehicle lost power on an active highway with no warning, creating a collision hazard for myself and other drivers. The failure has been confirmed by the dealership. Hyundai Motor America acknowledged the engine failure falls under the TXXI Settlement Agreement and offered a buyback or cash settlement. However, Hyundai has had physical possession of my vehicle since June 15, 2026 and has repeatedly failed to provide a written buyback offer despite multiple commitments to do so. Prior warning signs included the engine and EPS lights activating at the moment of failure. No prior warning lamps appeared before that day. The vehicle has 2 open safety recalls as of the date of purchase in November 2025.

NHTSA ID

11747461

Incident

May 22, 2026

Knock sensor needs to be replaced upon evaluation of an inspection on March 27, 2026. It failed a mission codes and upon my understanding the knock sensor one circuit range performance pink wonder single sensor is an engine failure as well as I did an ODB test myself on May 19 of 2026 for the Knox sensor as well and the check engine dominator reading at 2111 the the code indicated that bank one Knox and electrical circuit was out of it upper range or had it perform problem for a predetermined period of time and the code is P0326 and the secondary DTC is a combustion vibration sensor a circuit range performance which affects the powertrain. Also, I have switches with the electrical features in the vehicle as far as the ABS and the steering wheel controls and glitching for the cigarette adapter and plug-in area as well on top of the rear passenger side window, having issues with going up and down.

NHTSA ID

11744374

Incident

May 19, 2026

Vehicle experienced sudden loss of motive power while merging onto interstate I accelerated to enter traffic and all dashboard warning lights illuminated at once. Engine shut off immediately with no prior knocking,smoke, or warning. Car coasted to shoulder with complete loss of power steering and power brakes. After incident vehicle will not crank or restart , push -button start activates accessories but engine does not turn over when brake is pressed. Vehicle has Campaign 953\Knock Sensor Detection system update completed on October 14 2020. This failure matches NHTSA PE-18-003 and Hyundai TSB 22 -EM-003H for Theta II Engine connecting rod bearing failure.This is a known safety defect causing sudden engine stall at highway speeds .. Dealer inspection is pending Vehicle is currently inoperable...

NHTSA ID

11742443

Incident

May 13, 2025

While merging onto the interstate my vehicle suffered sudden loss of motive power. All dash lights illuminated ,engine shut off instantly with no prior knock or warning.vehicle will not crank or restart.push button start activates accessories only .This matches TSB 22-EM-003H for connecting rod bearing seizure.No crash occured because I was able to coast to shoulder but loss of power steering/brakes at highway speed created a dangerous situation.

NHTSA ID

11742366

Incident

May 13, 2025

p1326, rod bearing failure and seizure of motor without warning.

NHTSA ID

11735237

Incident

May 1, 2026

I am reporting a pattern of systemic failures on a 2012 Hyundai Sonata Hybrid with approximately 131,000 miles. This is my second NHTSA complaint regarding this vehicle and manufacturer. Primary Safety Concern — Engine Wiring Harness: During a recent engine replacement at an authorized Hyundai dealership, technicians identified damage to the engine wiring harness and documented in writing that the owner “might have issues with drive ability.” The dealership declined to repair it under the same goodwill program used to replace the engine and returned the vehicle with this known defect unresolved. The harness directly controls engine operation, hybrid system communication, and overall vehicle control. On a hybrid vehicle, a compromised harness presents a serious and ongoing safety risk. This component is available for inspection upon request. Engine Failure: The hybrid system warning light appeared prior to failure. The vehicle was towed to an authorized dealership where diagnostic code P1326 confirmed engine failure. The manufacturer acknowledged this and replaced the engine under goodwill. Additional System Failures: A pre-scan diagnostic revealed simultaneous fault codes across six systems — engine, transmission, ABS, active hydraulic booster, battery management, and motor control unit — including codes U0293 and U1004 indicating lost communication with the hybrid powertrain control module across multiple systems simultaneously. Independent Safety Advisory: A separate independent repair facility documented in writing that the vehicle presented a severe wheel hub bearing noise and formally advised of an extremely dangerous driving condition. Prior NHTSA Complaint: My first complaint to NHTSA involved this same vehicle when the manufacturer refused to provide a loaner during an extended recall-related repair hold, requiring formal escalation before they complied. The wiring harness defect remains unrepaired. The vehicle is driven daily out of necessity.

NHTSA ID

11732884

Incident

Oct 3, 2025

The contact owns a 2012 Hyundai Sonata. The contact stated that while driving at an undisclosed speed, there was an abnormal burning odor coming from the vehicle. While depressing the accelerator pedal, the vehicle hesitated and stalled. The contact stated that the rear driver’s side brake light was inoperative. The failure occurred on several occasions. No warning lights were illuminated. The contact researched and was made aware of an undisclosed recall; however, the VIN was not included in the recall. The vehicle was taken back to the residence. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 168,000.

NHTSA ID

11732852

Incident

Mar 21, 2026

Mileage

168,000 mi

Vehicle: 2012 Hyundai Sonata Incident Date: August 14, 2024 Location: [XXX] Description of the Problem: The vehicle experienced a sudden and catastrophic fire without warning while in normal use. There were no prior warning lights, messages, or symptoms before the incident. The failure appears to have originated from the electrical system and/or engine (exact cause UNKNOWN), which resulted in the vehicle igniting unexpectedly. Safety Risk: This failure created an immediate and life-threatening safety hazard to all occupants. The vehicle caught fire suddenly, leaving no time to react or prevent injury. There was no crash or external cause associated with this fire. The incident required emergency response from Butts County Fire and Emergency Services, who generated an official report. Injuries and Trauma: My son suffered burn injuries to his fingers, requiring emergency medical treatment. There is neurological damage to the fingertips, indicating lasting physical injury. In addition, my son experienced significant psychological trauma due to sudden exposure to a life-threatening vehicle fire, including acute emotional distress during the incident and ongoing fear associated with vehicle safety. This demonstrates the extreme danger posed by a sudden, unpreventable vehicle fire. Inspection / Confirmation: The incident was documented by Butts County Fire and Emergency Services. At this time, manufacturer inspection is UNKNOWN, dealer inspection is UNKNOWN, and insurance inspection is UNKNOWN. Warning Signs Prior to Failure: There were no warning lights, messages, or symptoms prior to the fire. The failure occurred suddenly and without notice. Defect Pattern Concern: This incident is consistent with known issues involving Hyundai Sonata vehicles, including engine and electrical system failures and reports of vehicle fires. This complaint is submitted to request a formal investigation. Prior Hyundai fire defects reported for this model. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FO

NHTSA ID

11729048

Incident

Aug 14, 2024

I purchased a used 2012 Hyundai Sonata. Within about 2 weeks it broke down while I was in the far left lane of the freeway. The car suddenly stopped accelerating and made a very loud knocking noise. Thankfully I was able to put on my hazards and make it to the right shoulder without getting into an accident but as soon as I pulled over it shut off and the panel lights all came on. Evidently there was a recall on an engine rod and the previous owners advised they were not aware of it. Hyundai has declined the repair on the recalled engine several times and their reasons keep changing. First they said I was missing records (admittedly I was missing one record but then provided it to them), then they stated excessive neglect due to the condition of the valve train (I saw pics of the valve train and is in good condition), and now they state because the KSDS wasn't installed. From what I understand, being the second owner, if I can prove the upkeep of the vehicle the extended waranty should cover the repair. I even have the letter from the car mechanic stating the vehicle was maintained and in good condition. It seems a lot of good people are getting declined for repairs on these faulty engines. I have many more documents I could provide showing all of the services done and communications with the company. Due to the size limit I included these ones for your review. Thank you so much for any help you can provide.

NHTSA ID

11728889

Incident

Feb 19, 2026

While driving, the vehicle experienced sudden engine malfunction. The car entered limp mode, lost power, and produced a loud knocking noise from the engine. The failure occurred without warning and created a safety risk because the vehicle could not accelerate properly in traffic. This increased the risk of being rear-ended or unable to move out of dangerous situations. The issue appears to involve the engine (possible internal failure). The vehicle is currently at an authorized dealership and is available for inspection upon request. The problem has been confirmed by the dealership during inspection. The vehicle has been under diagnosis for over three weeks. There were no prior major warning signs before the failure. At the time of the incident, the vehicle suddenly lost performance, entered limp mode, and began making abnormal engine noise. This issue is consistent with widely reported engine defects in similar vehicles. Despite this, the manufacturer has denied coverage and attributed the issue to maintenance, even though regular maintenance was performed. This is a serious safety concern due to sudden loss of power while driving.

NHTSA ID

11726701

Incident

Mar 4, 2026

While I was driving my car wouldn’t go no higher than 60mph and kept dropping speed but I came to a stop and when I stopped the car was smoking. I heard knocking noise and rumbling noise on the passenger side. It wouldn’t start again

NHTSA ID

11726267

Incident

Mar 9, 2026

My 2012 Hyundai Sonata recently had an engine replacement completed under a Hyundai recall. Immediately after the recall repair, the vehicle began shaking while driving, produced a burning smell, and the air conditioning stopped working, none of which occurred prior to the recall repair. These symptoms started immediately after the engine replacement, indicating a possible improper or unsafe installation. I believe the vehicle is unsafe to drive due to the burning smell and shaking. I contacted Hyundai Customer Service and was told the issue must be resolved with the dealership. However, the dealership has refused timely inspection, has dismissed my safety concerns, and has declined to provide a rental or loaner vehicle, leaving me without safe transportation. This is a post-recall safety issue, and I am concerned about the risk of fire or mechanical failure due to the burning smell and vehicle instability. I am requesting this issue be formally investigated.

NHTSA ID

11716306

Incident

Feb 3, 2026

The contact owns a 2012 Hyundai Sonata. The contact stated that the vehicle was experiencing excessive oil consumption, which required the oil reservoir to be refilled after 3-4 weeks. Additionally, there was no warning light illuminated. The contact stated that upon taking the vehicle to Jiffy Lube for a top off, the mechanic would inform the contact that the oil reservoir was empty and needed to be refilled. The vehicle was not taken to the dealer. The vehicle was not repaired. The manufacturer was informed of the failure. The failure mileage was approximately 158,000.

NHTSA ID

11707491

Incident

Dec 29, 2023

Mileage

158,000 mi

The contact owned a 2012 Hyundai Sonata. The contact stated that while driving to her residence at unknown speeds, the vehicle suddenly caught fire while making a U-turn. The brakes and emergency brake were inoperable. The seatbelt was inoperable. The driver jumped out of the window. A pedestrian attempted to alert her of the fire. The vehicle exploded after exiting the vehicle. The contact sustained an injury to her leg, but no medical attention was provided. The fire department extinguished the fire. A police report was filed. There was no report of a crash or airbag deployment. The vehicle was towed to a tow lot. The local dealer was contacted, but the vehicle was not diagnosed or repaired. The manufacturer was contacted, but no assistance was provided. The failure mileage was approximately 136,000. The vehicle was auctioned off by the towing company.

NHTSA ID

11702697

Incident

Oct 10, 2025

Mileage

136,000 mi

The engine in my Hyundai Sonata (replacement engine VIN [XXX] ) experienced a complete internal failure. The component that failed is the 2.4L Theta II GDI engine, which is known for issues related to metal debris, oil restriction, rod bearing wear, and resulting piston and compression failure. The failed engine is currently at the dealership (Carolina Hyundai) and is available for inspection upon request. My safety was put at risk because the engine lost power unexpectedly, ran extremely rough, and became inoperable. A sudden loss of power while driving could have caused a crash, especially in traffic situations. The problem has been reproduced and confirmed by the dealership. They performed a compression test and found all cylinders at extremely low PSI (35–45 psi). The dealer stated the engine cannot perform the required bearing clearance test due to the level of internal damage. Hyundai Corporate initially declined assistance, calling it a piston failure, but the symptoms and damage are consistent with the known Theta II recall issues. The vehicle has been inspected by the dealership, and all diagnostic information has been submitted to Hyundai under PA Reference #XXX. Hyundai Corporate has not yet responded to me with a case manager. Before the engine failure, the vehicle had rough running and loss of power, but no warning lights or messages illuminated on the dashboard. Symptoms appeared shortly before the engine became undriveable. Based on the dealer’s findings and the engine’s known defect history, it is my assessment that the failure is related to the same issues described in Hyundai’s Theta II engine recall (Campaign 132). INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11700126

Incident

Jun 18, 2024

My 2012 Hyundai Sonata (VIN: [XXX] ) experienced complete engine failure at 241,433 miles on August 7, 2025. The failure aligns with known safety defect symptoms described under NHTSA Recall Campaign 15V568000 and 17V226000, which cite premature bearing wear due to metal debris during engine manufacturing. My vehicle had previously received the knock sensor update under Campaign T3G and failed the BCT (bearing clearance test), confirming bearing damage. Despite this, Hyundai denied my engine replacement claim, stating the issue was related to a fuel pipe and not a rod bearing issue—this is contrary to their own recall documentation and dealer diagnosis. Hyundai continues to deny engine replacement, in violation of their federal recall obligations under 49 U.S.C. §30120. Their refusal endangers public safety by ignoring engine failures that can lead to stalling and crashes. I request NHTSA intervention to compel Hyundai Motor America to comply with federal law and perform the necessary recall repairs on my vehicle. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11695628

Incident

Jul 25, 2025

My 2012 Hyundai Sonata cut off and stopped working! The vehicle locked up in the middle of a main street and would not start back up causing a very unsafe situation. There were no check engine lights on or anything at the time of the incident I immediately had the vehicle towed and inspected it has been determined that the engine is failing! Upon research I found out that these engines have had recalls in the past. Carfax shows that the vehicle has been taken in for routine maintenance and oil changes when needed. I am looking to see if the engine replacement could be covered for this vehicle.

NHTSA ID

11695453

Incident

Oct 14, 2025

My engine seized on the highway on my way home from work. The service department has been horrid. They lied about who the manager is. They lied about the reason behind not wanting to honor the recall. They are rude - threatened to tow my car today after I waited 6 days to hear back from them about the issue with my car and determination. Was extremely rude. Stated that they were not honoring the recall because there was obvious signs of my engine being tampered with or certain parts on my engine, but could not provide a name of the part or a serial or model number so that this could be verified. I need this addressed immediately.

NHTSA ID

11695169

Incident

Oct 17, 2025

Vehicle loses power while driving making it unsafe to drive, it can cause an accident in certain conditions like when passing another vehicle or crossing a street. There is a recall for this issue.

NHTSA ID

11692354

Incident

Aug 30, 2025

Driving came to a stop ,light turned green made a U-turn to go to the gas station heard a pop noise smoke came from inside the car tried stopping it but the brake pedal sunk into the ground pressed my emergency brake it was seized wouldn’t go down (never had that issue my brakes always work ) I smelled brake fluid and seen the abs light on the dash then the power started to go out and my girlfriend almost got trapped in the car

NHTSA ID

11691470

Incident

Oct 5, 2025