2017 Hyundai Santa Fe Engine Problems

Immediately following the mandatory Hyundai Servie Campaign Update 9C2-ECU THETA 11my vehicle began exhibiting severe hesitation, very rough idling, jerking at slow speeds and when gear changes, difficulty going up inclines and almost feel at times as though it is about to lose power which poses life threatening situations especially when turning into traffic. I have reported it to the dealers who never once test drove the vehicle but said to me that they did and could find no problem, however they did make me pay for repairs which never fixed the problem. I returned three times with the same issue. They recommended a Fuel Induction Service and a Auto Trans Service. Spark plug change. Igniton coils change. Nothing worked!

NHTSA ID

11767289

Incident

Jun 17, 2026

Component/System Failed: Engine assembly (Theta II 2.4L GDI) and Exhaust/Catalytic Converter. Description: The vehicle suffered a failure associated with the known Theta II engine defects. Engine oil consumption and internal engine wear directly led to unburned fuel and debris entering the exhaust stream, resulting in severe catalytic converter restriction/failure. Safety Risk: The combined failure caused sudden loss of power while driving, engine stalling, and significant driveability hazards, creating an immediate risk of a rear-end collision on public roads. Confirmation & Inspection: The failure was confirmed and diagnosed by a certified service facility. Replaced components and diagnostic documentation remain available for inspection upon request.

NHTSA ID

11765645

Incident

Sep 2, 2026

My son was driving the vehicle normally. There were no issues, warning lights, abnormal feel to the drive, and no odd noises. Suddenly, all of the warning lights on the dashboard lit up, acceleration dropped and he could no longer accelerate. He pulled off the main road and there was a burning smell and the vehicle was inoperable.

NHTSA ID

11765544

Incident

Sep 11, 2026

Service update 9C2. Car hesitates or slightly bucks on a cold start. No remedy to fix yet.

NHTSA ID

11765542

Incident

May 6, 2026

Hyundai performed recall #9C2, on 7/2/26. Since that time, the engine has a full time miss. When it is cold, it will hesitate, kick and buck. Hyundai is aware of this. Their solution is to warm the car for 3 to 5 minuets before moving. What happens if there is an emergency and you can't wait? Possible accident with injuries trying to pull into, or cross traffic! I have filed a case with Hyundai, and they just update that they are aware and working on a solution with no expected date for the software fix. This is a serious problem, and they need to fix SOON! Also, when an engine runs like this, over a period of time it will destroy the catalytic converter. Who's going to pay for that??

NHTSA ID

11765456

Incident

Jul 2, 2026

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.

NHTSA ID

11763180

Incident

Aug 18, 2026

-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)

NHTSA ID

11762822

Incident

Jun 4, 2026

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.

NHTSA ID

11761955

Incident

May 26, 2026

Cold-Start Hesitation & Rough Shifting: Following the 9C2 ECU update, my vehicle is experiencing a brief period of throttle hesitation, rough shifting, or jerky transmission behavior specifically during cold-start operations.

NHTSA ID

11760934

Incident

Aug 21, 2026

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)

NHTSA ID

11760878

Incident

Aug 25, 2026

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.

NHTSA ID

11759120

Incident

Aug 11, 2026

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.

NHTSA ID

11758839

Incident

Apr 24, 2024

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.

NHTSA ID

11758520

Incident

Aug 11, 2026

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.

NHTSA ID

11758504

Incident

Jul 2, 2026

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.

NHTSA ID

11758484

Incident

Apr 28, 2026

We have been involved with an Oil Consumption problem since 2025 maybe earlier. No leaks just an over use of oil. I have had to fill it myself or take it to the dealer. They did testing and di some kind of cleaning that took 8 hours. We still have the problem and while driving the whole car shut down. No power in the middle of a highway. This has now happened twice and the first time we had to call AAA for help. It showed an engine sign and we checked the code. First it was an small air leak but they didn't find anything. It came up again, same message so we replaced the gas cap, but the oil was still disappearing and the car had shut down again. I spoke with the Hyundai corporation and they said to do the combustion cleaning again. So we set it up but found out that we had to pay for it so we declined. They refused to do anything about the car. We later found there were other cars made by the same company with the same problem. I did some research and they have had an Oil Consumption problem for quite a while. Now the Catalytic Converter is showing up as having problems. Well that's where the oil goes and can shut down the car due to airflow. They never disclosed it to us face to face, we had to find out about it after the the warranty was up. That was very dangerous to have stopped on a highway.

NHTSA ID

11756697

Incident

Jun 24, 2026

Complete unmitigated loss of acceleration and power while traveling at highway speeds, creating an immediate life-threatening road hazard. Following a warranty engine replacement and mandatory dealer software flash at Clay Cooley Hyundai (Sherman, TX), the vehicle began experiencing powertrain communication issues. While operating the vehicle at 65 MPH on the highway, the vehicle completely failed to accelerate and lost propulsion power, nearly resulting in a catastrophic rear-end collision with an oncoming 18-wheeler semi-truck. Dealership diagnostics claim "no trouble codes present," but live data telemetry confirms the High-Pressure Fuel Pump (HPFP) is actively commanding and delivering a dangerous 1,600 PSI to the fuel rail at hot idle. This abnormal fuel delivery is paired with a severe powertrain stutter in 3rd gear. Service personnel at multiple locations confirm a widespread, high volume of transmission failures and severe drivability issues specifically tied to this recent Hyundai software update. Corporate has denied repair coverage. The vehicle remains an active highway safety hazard and is completely undrivable.

NHTSA ID

11756411

Incident

Jul 8, 2026

The 9C2 campaign software update introduced dangerous vehicle hesitation and unpredictable gear changes in active traffic, presenting and immediate crash hazard

NHTSA ID

11753154

Incident

May 20, 2026

On June 10, 2024 at 107,129 miles Hertrich Hyundai dealership of New Castle inspected my vehicle and submitted a request to Hyundai for engine replacement under the recall settlement of the Theta II Engine Settlement. Hyundai denied the request because of the rebuilt title, even though the rebuilt title resulted only from prior Roof damage unrelated to the engine, powertrain, or recall issue. After continuing to seek assistance from Hyundai, my engine ultimately seized and suddenly stopped working on May 10, 2026, while driving on the highway with my two children. The vehicle lost power and stopped in traffic, creating a dangerous situation and causing my children extreme fear and distress. Had Hyundai honored the Theta II Engine Settlement when I first requested assistance, this failure could have been prevented. I request that Hyundai honor the Theta II Engine Settlement and replace my defective engine at no cost to avoid any future problems. My Hyundai Santa Fe is covered under the Theta II Engine Settlement. For over three years, I repeatedly contacted Hyundai after experiencing symptoms consistent with the known Theta II engine defect. Hyundai failed to provide meaningful assistance, did not properly process my requests, and denied coverage solely because of the vehicle’s rebuilt title.

NHTSA ID

11753050

Incident

Jun 25, 2026

I own a 2017 Hyundai Santa Fe Sport 2.4L (VIN: [XXX]). On XXX, my vehicle received Campaign 9C2 (ECU software update for Theta II emissions improvement). Shortly after this update, I began experiencing a drivability issue that did not exist beforehand. Description of the issue: The problem occurs only after the vehicle has been sitting long enough for the engine to become completely cold, typically overnight. During approximately the first 1/4 mile of driving, the vehicle intermittently jumps, surges, or lurches while accelerating normally. Once the engine warms up, the symptom completely disappears and the vehicle drives normally for the remainder of the trip. There are no warning lights, no check engine light, and no diagnostic messages. The Hyundai dealer has had the vehicle for nearly a week but has been unable to reproduce the concern. Because the issue only occurs during the initial cold start and first portion of the drive, I am concerned that it may not have been tested under the same conditions in which I consistently experience the problem. I am not claiming that Campaign 9C2 caused the issue, but the timing is notable because the symptom began only after the ECU update was performed. I am requesting Hyundai's assistance in determining whether: - the ECU update was installed correctly, - any required adaptation or relearn procedure is incomplete, - there are any related Technical Service Bulletins or software updates, or - additional diagnostics should be performed during a true cold-start drive with live data recording. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11751838

Incident

Jun 11, 2026

On July 4, 2026, I was driving 2.5 hours from home. My car stopped after about an hour of travel. The car shook and the check engine light came on as the car shut down. There were no warning lights on in my vehicle. I have oil change records. My car had burned through all the oil in an hour. This is not a new problem with this model Hyundai. Every group I went to discuss the problem online all had customers who reported their vehicles suddenly started burning oil quickly which resulted in damaged motor with no warning lights in the dashboard. I had to have my car towed from out of town to the dealership. The dealership that said I had extended warranty on parts of the motor. However upon checking the motor, they said it wasn't covered. I filled out a claims report with Hyundai motors who looked into the problem and also said it's not covered under warranty. This is a known issue of Hyundai with a failure to warn of low oil in the car's warning center. This is a fault of Hyundai. I've taken good care of my car and just paid $1000 for new tires on July 2, 2026 before my trip. The dealership quoted me a price of $3500 to replace the motor with a used one. It would also require 16 hours of labor which I Believe is $200 an hour. I believe they should replace the motor due to faulty systems. My car has 107,000 miles on it, but whenever I've gone to have it checked out, everything checked out fine even at the dealership. Also, this is a known issue that Hyundai is refusing to address with their customers.

NHTSA ID

11751827

Incident

Jul 4, 2026

After having the Service Campaign 9C2 ECU SOFTWARE UPDATE FOR THETA II EMISSIONS IMPROVEMENT, TSB 26-01-013H-2 done, my vehicle started having driveablity issues. On a normal, cold start the engine's RPMs go up really high, so I take my foot of the gas and the revs drop, almost stalling the car, and then the car bucks. I put my foot back on the gas pedal, and the engine revs really high again and takes off. If I try to drive normally, the car bucks and runs rough. My car also revs a lot higher during highway driving, than it did before the update. All of this is also causing terrible gas mileage. My car did nothing like this until I had the 9C2 update.

NHTSA ID

11750493

Incident

Jun 17, 2026

Hyundai Campaign 9C2 recall update: Took my vehicle in to have the Hyundai Campaign 9C2 recall update performed on the vehicle on June 9th, 2026. Since the update the vehicle is hesitant/jerky upon first drive of the day or anytime it sits more than a few hours. Occasionally it will do this while I am driving. I feel it is a saftey risk because this could cause my vehicle to abruptly hesitate without braking and cause someone to hit me, or worsetransmission to fail while at highway speeds. I took it back to the dealer that performed the required update around june 23rd 2026 and informed them of the problem caused by the 9C2 campaign update.I got the we don't know anything about it causing problems runaround. Even though it has been documented that dealers were notified of this problem. They then wanted to charge me a $100 diagnostic fee to see if it might be something else, I declined that because I know it is from this update. My vehicle ran perfectly fine and smooth before this update was applied and no CEL lights are on. I did this update because it was required to be done by Hyundai. When I started researching why my vehicle was hesitant/jerky after the update is when I found that anyone that did this update is having these same issues, and it has been happening for a while now and Hyundai corporation has done nothing to correct this problem other than tell us to sit for at least 3 minutes or more before driving it. That does not help when it does it even after driving for a bit and possibly creating transmission problems.

NHTSA ID

11748778

Incident

Jun 9, 2026

We are driving on the highway and the engine just stop working but all lights are still working. I am trying to put gas but it seemed that the engine completely shuts off dangerously without warning. This put my family at risk because there were a lot of big trucks beside us. Theta II 2.0L Turbo engine just stalled I believe this has been around . Can you please help us.

NHTSA ID

11747482

Incident

Jun 29, 2026

The contact owns a 2017 Hyundai Santa Fe. The contact stated that after an unknown Emission recall was performed on the vehicle, the vehicle started sputtering at start-up and then while driving. There was no warning light illuminated. The dealer was notified of the failure and informed the contact that it was a known failure after the Emission recall repair. The contact was informed that the manufacturer was working on a fix for the issue. Additionally, the contact was advised that the recall repair was optional, but the contact had opted to have the vehicle repaired under the recall. The manufacturer was contacted several times, but no assistance was provided. The failure mileage was approximately 78,000.

NHTSA ID

11747342

Incident

Jun 9, 2026

Mileage

78,000 mi