2012 Hyundai Sonata problems

ENGINE

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 complaint #11754020 — an unverified report by a vehicle owner.

ENGINE

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 complaint #11753470 — an unverified report by a vehicle owner.

FUEL/PROPULSION SYSTEM

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 complaint #11753470 — an unverified report by a vehicle owner.

ENGINE AND ENGINE COOLING

See attached document for complaint.

NHTSA complaint #11752062 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

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 complaint #11750478 — an unverified report by a vehicle owner.

ENGINE

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 complaint #11750478 — an unverified report by a vehicle owner.

ENGINE

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 complaint #11747461 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11744374 — an unverified report by a vehicle owner.

AIR BAGS

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 complaint #11744374 — an unverified report by a vehicle owner.

ENGINE

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 complaint #11744374 — an unverified report by a vehicle owner.

ENGINE

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 complaint #11742443 — an unverified report by a vehicle owner.

ENGINE

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 complaint #11742366 — an unverified report by a vehicle owner.

POWER TRAIN

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

NHTSA complaint #11735237 — an unverified report by a vehicle owner.

ENGINE

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

NHTSA complaint #11735237 — an unverified report by a vehicle owner.

EXTERIOR LIGHTING:BRAKE LIGHTS

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 complaint #11732852 — an unverified report by a vehicle owner.

ENGINE

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 complaint #11732852 — an unverified report by a vehicle owner.

ENGINE

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 complaint #11732884 — an unverified report by a vehicle owner.

SEAT BELTS

The contact owns a 2012 Hyundai Sonata. The contact stated that while driving at an undisclosed speed, the driver’s side seat belt unexpectedly detached. Several attempts were needed to secure the seat belt while driving. The contact stated that while the vehicle was parked, the driver’s seat belt became inoperable and failed to latch properly. An independent mechanic was contacted. The vehicle was not diagnosed or repaired. The dealer was also contacted. The vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The approximate failure mileage was 127,819.

NHTSA complaint #11731186 — an unverified report by a vehicle owner.

ENGINE

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 complaint #11728889 — an unverified report by a vehicle owner.