2017 Hyundai Santa Fe

Vehicle was brought to an authorized dealership for service, and while there Campaign 9C2 (ECU Software Update for Theta II Emissions Improvement) was performed. Immediately following this software update, the vehicle developed drivability degradation, specifically engine stutter/hesitation and rough transmission shifting during cold starts. When attempting to accelerate in the first few minutes of driving, the vehicle delays engagement and then suddenly surges or lurches forward unpredictably. This creates a safety hazard, as the unpredictable power delivery and lag prevent the vehicle from accelerating safely when merging into traffic or turning across oncoming lanes, placing occupants at an immediate risk of a collision. The software logic error is fully reproducible every time the vehicle has sat long enough to cool down. The dealership confirmed the update was applied. There were no warning lamps or symptoms prior to the 9C2 update; the failure was caused directly by the manufacturer's campaign software modification to the Engine Control Unit (ECU). The vehicle and its ECU are available for inspection upon request.

-The primary mechanical failure is a burned exhaust valve in Cylinder 2, which has resulted in 0 PSI compression and a persistent engine misfire. This severe top-end valve degradation occurred as a direct consequential result of a chronic, underlying defect in the engine's internal oil-delivery and consumption systems. The vehicle is currently fully assembled, intact, and available for immediate inspection upon request at Brown-Daub Hyundai. -The vehicle suffered a sudden, severe loss of motive power while operating in traffic due to the cylinder drop, triggering a sudden transition into a dangerous operating state. The extreme oil consumption rate (burning 5 to 6 quarts of motor oil every 3,000 miles) created an ongoing, severe risk of sudden highway stalling, catastrophic moving component seizure, and potential engine bay fire due to extreme internal operating friction and chronic oil starvation. -Failure has been confirmed by two independent automotive facilities: Independent Confirmation: On XXX, [XXX]’s Service Center performed a diagnostic scan and an engine compression test, formally documenting diagnostic trouble code P030200 (Cylinder 2 Misfire) and verifying 0 PSI compression in Cylinder 2.Dealership Confirmation: On XXX, the service manager at Brown-Daub Hyundai executed a formal electronic and mechanical inspection under Repair Order #XXX, duplicating the failure and logging active trouble codes P0301, P0302, and P0128. -Symptoms first appeared progressively through an accelerating, severe oil consumption defect, which was documented during multiple routine maintenance: XXX oil consumption (115,865 mi): XXX (119,601 mi) no external leaks: XXX (125,502 mi) excessive oil consumption:XXX (135,116 mi) excessive oil consumption:XXX (133,022 mi) P0420 Cat Code: XXX (approx. 137,000 mi)engine rough-riding, shaking, & violent misfires began, preceding the mechanical breakdown INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

On May 26.2026, Southern States Hyundai performed mandated Service Campaign 9C2 (Theta II Emissions Improvement). The software immediately caused drivability degradation and a catalytic converter failure, mirroring the defects Hyundai acknowledged to the NHTSA on May 18, 2026. Corporate customer care is using an unrelated oil consumption testing protocol to deflect liability and charge me $1,400 for the testing and/or $4002 for the catalytic converter out of pocket for damage caused by their own recall software. This hesitation is a severe safety risk when accelerating into traffic.

My truck began emitting a strong oil odor on XXX. I took it to Amato in [XXX], where I was told the oil pan was leaking. They replaced the oil pan, and I paid for the inspection as well. About an hour after picking up my truck, the check‑engine light came on. I returned to the dealership, and they then said additional repairs were needed, even though I had already paid $2,211.57 for the work they claimed was necessary. At that time, my truck had 145,776 miles on it. Because the manager at [XXX] refused to address my concerns, I was told to go to another Amato location, and I was effectively blacklisted from the first dealership. I went to Amato Glendale, where I experienced the same issues. They fixed only one of the problems, and that was only after I contacted Hyundai corporate. My truck continued to have oil‑consumption issues. Amato required me to complete a three‑month, 1,000‑mile oil consumption test before they would consider providing assistance. I completed the test as instructed. Now, however, they are saying that due to the age and mileage of my truck, they will not cover the engine replacement — even though the problems began at 145,000 miles, not 156,000. Other drivers have reported that Hyundai delays necessary repairs until major engine damage occurs, and I believe that is exactly what has happened in my case. There was also a suspension recall that applied to the 2018 model but not the 2017. Amato Hyundai covered part of that repair only because I contacted corporate again. My current complaint is about the failing engine and Amato Hyundai’s lack of responsibility in properly diagnosing and repairing my truck. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

My 2017 Hyundai Santa Fe, purchased new from Lynnes Hyundai in February 2017, has approximately 93,000 miles. The vehicle previously developed a significant oil-consumption/engine problem that was diagnosed by Hyundai, and Hyundai replaced the engine with a remanufactured engine. Approximately two weeks after the engine replacement, the check-engine light illuminated and DTC P1326 was identified. The dealership replaced the knock sensor. Approximately two weeks later, the check-engine light illuminated again with a recurring P1326 condition. The vehicle is currently at Lynnes Hyundai and has been there approximately three weeks while they attempt to determine the cause. Hyundai Techline is involved. Prior to the current repair visit, while traveling approximately 60 mph, the vehicle experienced a very forceful hesitation that jerked the vehicle. I immediately slowed down and pulled onto the shoulder. The vehicle continued to hesitate intermittently while I drove slowly to safety. I was concerned that the vehicle could lose power or shut down while I was driving at highway speed, creating a risk of a crash. The recurring P1326 condition has been confirmed by the Hyundai dealership. The vehicle and engine have been inspected by Hyundai/Lynnes Hyundai multiple times, including after the engine replacement. The current recurring condition has not been resolved. The check-engine light is the warning lamp associated with the current condition. I do not know the underlying cause of the recurring P1326 condition; Hyundai is currently attempting to diagnose it. The vehicle is currently available for inspection at Lynnes Hyundai.

My 2017 Hyundai Santa Fe 3.3L V6 (148,000 miles) has documented oil consumption and a recurring DTC P0278 (Cylinder 6 Contribution/Balance). Hyundai's formal oil-consumption test confirmed oil consumption, but said it was below the threshold for combustion-chamber cleaning. The check-engine light and P0278, and losing acceleration ability continue to recur. The vehicle is available for inspection. Hyundai has confirmed the oil-consumption issue but has not determined the cause of P0278 or performed the TXX8 engine inspection I am requesting. I am concerned about worsening engine performance, loss of power, or engine failure, particularly given Hyundai's history of engine-bearing issues with certain 2017 Santa Fe 3.3L engines. I am not claiming diagnosed bearing failure; I am requesting a TXX8 inspection to determine whether an eligible engine condition exists. I have contacted both the dealership and Hyundai Corporate, but have been told I must repeat the oil-consumption test. At 148,000 miles, I am requesting prompt inspection before the 150,000-mile TXX8 limit and covered repair/replacement if an eligible condition is found.

There is a class action lawsuit for the Theta Engine in some Kia and Hyundai vehicles and my type of vehicle falls into this lawsuit category. I drive a 2017 Hyundai Santa Fe Sport and what the lawsuit described what happened to my vehicle, it seized up and you’re supposed to have a lifetime warranty for this problem. I submitted all the paperwork and Norman Hyundai sent videos it was seized up but denied my claim so I have a car that no longer drives with a car loan still so can’t buy a new vehicle. I was told they didn’t see oil additive anytime but their own business this in March ‘26 and May ‘26. It states on the lawsuit if anyone’s in the class action lawsuit they are covered if this happens to your vehicle. Also, part of the lawsuit is the oil consumption and how much it’s eating gas and then it seizes possibly or catch fire and my car was barely getting a 1,000 miles and it would be empty so couldn’t keep up always checking it and the car seized up due to what’s supposed to be covered.

After the update earlier this summer for an emissions issue, my car, a 2017 Hyundi Santa Fe Sport, has not run right. When it is cold, the first trip on the day, it hesitates and sputters to an extent that it is not safe on the nearest highway where the speed limit is 35. We have been compensating by driving slowly around the neighborhood for a few minutes, and then it's fine. It has been happening since the update of service campaign 9C2, the "Theta II Emissions Logic Improvement" recall. The local Hyundai dealer has been unable to provide a fix. We just picked it back up today, 8/21/26, after deciding against their latest idea, a fuel injector treatment for $200. Based on other examples I've read with similar or identical issues after the recall software update, I have concluded this is a safety issue that Hyundai must resolve.

Directly after the dealer, Johnson Hyundai of Apex, completed Service Campaign 9C2 on 4/28/26, my vehicle began sticking, surging, and harshly changing gears. I have followed up with the dealer multiple times. They said they are not getting back any diagnostic error codes (outside mechanic shop also confirmed they're also not seeing error codes), but went ahead and recalibrated the ECM. They told me to drive for 200 miles and the issue should be resolved. I have now driven 1,500 miles and the issue persists. I'm now seeing Hyundai put out a 'Driveability Communication" about this issue, but there is no proposed fix/recall. This issue did not exist before this service campaign was performed by the dealership.