Hyundai Sonata check engine light comes on

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 22, 2026 · Fuel system · LA

The fuel tank assembly became pressurized with compressed air due top worn purge control system check valve. This caused the tank to deform and the deformation of the tank led to the fuel pump being pushed out and the back seat of the car was completely unattached and no longer secured. There was a strong presence of gas smell in the car as well. The check engine light came on and the car began to drive poorly. It was taken directly to a Hyundai dealership where it remains as of today. This could have resulted in the car catching on fire and potentially killing everyone in the car. My [XXX] daughter and 2 friends was driving the car from Louisiana to Mississippi when this occurred. The dealership in MS told her she needed to call and find someone to come and get her because the car was not safe to drive. My daughter was stranded in another state and had a college friend come and get them since I did not have a car and I was in Louisiana. After several hours her friend was able to pick them up which she remained stranded in MS for an additional 4 days. I had to get a friend to meet them halfway and bring her home because the dealership said there was nothing they could do to assist with transportation. This occurred on [XXX]. My car remains at this dealership in MS with only the testing to say the gas tank test failed and the car could not be driven. I was told Hyundai would offer a buyback on my vehicle because the repair was costly and time consuming. I have not been reimbursed for my transportation expenses through Uber as of today. I was told I could rent a car and they would reimburse my expense after I submitted a receipt and waited several weeks to process and then at least 2 weeks for the payment to clear. Either way I have received nothing. There was not any warning and the dash lights and poor engine running all happened at once. She drove straight to the dealership on [XXX]. We have not been treated fairly with this situation. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S

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 5, 2026 · Engine · UT

I was driving on the freeway about 100 miles outside of Boise, ID when the vehicle went into limp mode and a flashing check engine light came on. I had it towed to the Hyundai dealership in Boise where they ran a diagnostic check and it came back with a P1326 code, which is the issue related to the engine/ball bearings. They said it passed the bearing clearance test (BCT) so they updated the software and gave the car back. I picked it up a week later and while driving it from Boise to Salt Lake City (where I live), it went into limp mode again with a flashing check engine light. This happened about 100 miles north of Salt Lake City. I had it towed to a dealership in Murray. They indicated it passed the BCT again, but they replaced the knock sensor and did an oil change and gave the car back. I picked it up, and the next day, while on the freeway, the same thing happened again. I took it back to the dealership. They indicated the knock sensors they just installed the day before needed to be updated, so they updated the software for the knock sensors. I just picked it up, and within 45 seconds of being on the freeway, it went right back into limp mode with the flashing check engine light. This has happened 4 times now, on the freeway forcing me to immediately get over, and I have almost gotten into two separate accidents because of this. Hyundai says they will not replace the engine because it keeps passing the BCT. The vehicle is not safe to drive and it is likely causing irreparable damage to the other systems of the car.

Filed Oct 4, 2026 · Engine · UT

While driving on the freeway, the check engine light started flashing and the gas pedal became useless. This put the driver and the passenger of the car in massive danger as they could no longer accelerate on the freeway. Luckily, they were able to get off the freeway without causing an accident. Upon reading the code at an auto shop, they discovered that it was P1326 or a knock sensor issue. This malfunction caused the car to go into limp mode and put the passengers in serious danger. Several calls to the Hyundai Service Center were made yesterday (Saturday, October 3rd). However, not one was ever answered. They hope to be able to get the car to the dealership's service center as soon as possible, but the earliest appointment online is multiple weeks away. This same car was recently at the dealership service center for an internal engine oil consumption problem and thoroughly inspected. The car is up to date on all software and recalls. Even though a valve cover replacement fixed the oil consumption issue, the owners are now having even worse issues. This is the only car for a married couple who are both working and going to college full-time. This issue has been a severe complication to their scheduling, and they were put in harm's way on the freeway.

Filed Sep 23, 2026 · Brakes, Driver assistance · NY

While driving at highway speeds, the emergency brake system will apply and alert me. It’s happened twice now in the last 3 weeks. I’ve experienced a random loss of power while driving on the highway with no check engine light on the dashboard. Lastly, at lower speeds the car will randomly jerk while accelerating with no lights on the dashboard as well. I’ve gone to the dealership but they wanted to charge me a diagnostics fee to first look over the vehicle, which I don’t feel I should be on the hook for since the issue isn’t user caused.

Filed Sep 15, 2026 · Brakes, Engine · 140,000 miles · LA

The contact owns a 2022 Hyundai Sonata. The contact stated that the vehicle was repaired under the federal safety agency Campaign Number: 25V796000 (Fuel System, Gasoline); however, while driving 70 MPH and depressing the accelerator pedal, the vehicle decelerated unintendedly. The check engine warning light illuminated. The contact stated that upon depressing the brake pedal, the brakes failed to respond as intended. The manufacturer was notified of the failure and stated that the contact would receive a callback. The failure mileage was 140,000.

Filed Sep 11, 2026 · Engine, Fuel system · VA

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)

Filed Sep 10, 2026 · Engine · 90,000 miles · IL

The contact owns a 2019 Hyundai Sonata. The contact stated that while driving 55 MPH, the check engine warning light illuminated, and the vehicle went into LIMP Mode. The contact stated that the vehicle failed to accelerate above 58 MPH. The contact retrieved DTC: P1326 (Knock Sensor Detection System) at O'Reilly Auto Parts and stated that the knock sensor had previously been replaced. The failure mileage was approximately 90,000.