2018 Hyundai Santa Fe Sport: hesitation when accelerating

Filed Sep 15, 2026 · Engine · NE

My 2018 Hyundai Santa Fe Sport (2.4L Theta II GDI, VIN [XXX], approx. 110,000 miles) has suffered a chain of engine and emissions-system failures that create a loss-of-power safety hazard. At about 80,000 miles, Hyundai replaced the original engine under warranty for excessive oil consumption, a defect Hyundai has acknowledged across the Theta II engine family. After only about 20,000 miles on that replacement engine, the catalytic converter failed and set a P0420 code. The vehicle now bogs down, hesitates, and loses power under acceleration. This is dangerous when merging or accelerating into traffic, where a sudden loss of power raises the risk of a collision. A restricted or failing catalytic converter causes exhaust backpressure and abrupt power loss, and the underlying oil consumption also risks low-oil engine damage and stalling. A catalytic converter should last far longer. This premature failure is consistent with the well-documented Theta II pattern in which engine oil consumption contaminates and destroys the converter substrate. It indicates the replacement engine Hyundai installed is itself consuming oil and damaging downstream exhaust and emissions components. I reported this to the dealer and to Hyundai. Hyundai declined to cover the catalytic converter, treating it as unrelated, even though its own warranty engine replacement is the direct cause. I am filing so this safety-related failure is documented. No crash, fire, or injury has occurred. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Aug 26, 2026 · Engine, Fuel system · NJ

Bought this as a used vehicle with around 77k miles. The SUV was running fine for a little while until I drove onto the highway. It eventually began to bog down and there was hesitation and jumping instead of acceleration. This continued my entire trip home with the check engine light on. The car was only driven for about 300-400 miles in the time I had it. When I brought it to have an oil change, they found metal shavings in the oil. From what I’ve been reading, this has been a common problem for this vehicle. It has been sitting in a Hyundai service center for at least a month now with no real responses from Hyundai themselves. They told me they would not fix the problem due to lack of maintenance from prior owners and that they were marking my title (doesn’t make sense since I bought this with a clean title). According to what Hyundai told me, this issue was brought up by a previous owner in January 2026 with no repairs. How can you change the status of my title while refusing to repair a problem caused by a manufacturers defect?

Filed Jul 17, 2026 · Engine · TN

The Hyundai Theta engine is a bad design that has many recalls, a history of oil consumptions, and breakdowns that leave consumers in danger, on the roadside, and out of money. This engine has a design that causes worn engine components and high oil consumption causing reduced engine power, ruined spark plugs, and engine damage with no recourse as a owner. Recently, my family member had a hesitation that causes the car to run rough and display a check engine light. She was in traffic and the vehicle was stopping. Had this been on the interstate it could have been deadly. This IS NOT UNCOMMON for these vehicles. A quick Google search is nationwide proof of an issue with these vehicles and engines that the government needs to hold Hyundai accountable. This particular vehicle has been assessed by a Hyundai and confirmed it is consuming oil at a higher rate than normal, as many other owners have documented. With this most recent issue of stalling out, the mechanic indicated that excessive oil consumption entering the spark plug port has fouled the spark plugs as the design of the engine is flawed. The oil consumption was discovered at approximately 99,000 miles and several steps were completed to "fix" and confirm the issue. There is no "real fix" to the issue due to the inherent design of the motor. Again, this is not a new issue with these cars and there should be recourse that holds Hyundai accountable for bad and dangerous engines. The check engine light did come on as the vehicle began to stall and run rough in traffic.

Filed Apr 1, 2026 · Engine · 141,654 miles · KY

The contact owns a 2018 Hyundai Santa Fe Sport. The contact stated that while driving 30 MPH and attempting to accelerate, the vehicle hesitated, with the check engine warning light illuminated. The vehicle was driven back to the residence. The vehicle was not repaired. The dealer was not notified of the failure. The manufacturer was not notified of the failure. The failure mileage was 141,654.

Filed Feb 18, 2026 · Engine · CT

engine cut out on highway, check engine light flashing. Car would not exceed 50 mph on highway and would hesitate/jump trying to go up any hill/incline. Took to mechanic and vehicle had P1326 knock sensor code. There appears to be a service campaign (Campaign 966/T3G) for 2013-2018 Sanat Fe Sport vehicles, but when i enter my VIN campaign does not appear. This is a safety risk/hazard and should be covered by the campaign/addressed by dealer. Car has always been well maintained and adhere to service schedule.

Filed Apr 3, 2025 · Engine · SC

I purchased this car in December 2023. As 2024 happened, I had a routine maintenance check on the car. The oil was changed, all the fluids checked etc. It appeared fine. Within a year, I have to change the spark plugs twice and once again in 2025..That's isn't normal. The plugs were jet black. Oil is seeping out of the gas tank. Not natural. There is an OIL CONSUMPTION ISSUE. My mechanic had typed notes on my receipt on what the problem(s) had been. Every other week, I am adding oil to my car. It isn't paid for. I would like a recall established on my car. I am [XXX] and need a reliable car. I went to one HYUNDAI dealership, provided the information my mechanic had written. Refused to give me the oil consumption test. I paid $200 or $238 for an oil change and a plug of some sort. I am aware that there was a class action lawsuit against HYUNDAI in 2022 for the same issue for my car. Money was paid to those whom had this issue ( I read). I have problems with my legs and back. I really need help. I need a recall on my car. Approximately, maybe a little less, every 5000 miles, my engine light comes on. I know a faulty spark plug shake. I can't afford to buy a new or replacement engine that work. I have never contacted the federal safety agency before I purchased this vehicle. I did call HYUNDAI main customer service line and was informed a recall had never been issued for this problem. Yet, numerous owners had and still have this issue along with the car hesitating at time to start. That is a problem with my as well. I am not sure of the exact date the first set of spark plugs were replaced. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Jan 30, 2025 · Engine · MO

engine light came on while on highway got off highway to get to safe place vehicle being hesitation dealer says need engine

Filed Nov 23, 2024 · Fuel system · MI

Upon acceleration from a stopped or rolling stop the vehicle hesitates to propel causing a dangerous situation when entering traffic. Dealer claims its not bad and that the manufacturer is only going to suggest fuel injector cleaner. Fuel injector clener was tried with no improvement. Upon research i have found this to be a common problem with this model. This is not the first problem we have had related to this system. Programming has been adjusted in the past to fix another problem which tells me this could be a computer problem.

Filed Nov 4, 2024 · Engine · 58,000 miles · UT

The contact owned a 2018 Hyundai Santa Fe Sport. The contact stated that while his wife was driving 40 MPH, the accelerator pedal was depressed; however, the vehicle hesitated and stalled. The contact stated the check engine warning light was illuminated. The vehicle was taken to an independent mechanic and was diagnosed with engine failure. The contact was informed that the engine needed to be replaced. The contact then had the vehicle towed to the dealer where it was diagnosed and determined that the knock sensor needed to be replaced. The knock sensor was replaced and the vehicle was repaired. The manufacturer was made aware of the failure. The failure mileage was 58,000.

Filed Mar 25, 2023 · Acceleration, Engine · IL

The acceleration of the vehicle from a stop. Whether from a stop sign, stop light, even sometimes after slowing down after a turn. It hesitates while the gas pedal is still being applied. Causing the vehicle to slow and other vehicles are forced to brake. The engine does not rev and the tachometer does not move. There are no warnings lights or vehicle notifications. After several attempts to bring it to the dealership, they are never able to replicate the issue. The OBD scans show no issues. It has never been a constant problem, however it remains as a "hit or miss" issue. Could be days of no problems and then popping back up every stop.

Filed Nov 10, 2022 · Engine · 100,000 miles · MI

The contact owns a 2018 Hyundai Santa Fe Sport. The contact stated while driving 72 MPH, the vehicle inadvertently decelerated to 50 MPH. The contact then stated that the vehicle hesitated and stalled. Additionally, the contact stated that she turned off and restarted the vehicle; however, while driving at a slower speed, the vehicle stalled again. The checked engine and oil pressure warning lights illuminated. The vehicle was towed to the dealer where it was diagnosed that the engine needed to be replaced. The vehicle was repaired. The manufacturer was notified of the failure and the contact was provided a case number and informed that the vehicle was not under recall. The failure mileage was approximately 100,000.

Filed Jun 17, 2022 · Engine · 64,000 miles · CO

The contact owns a 2018 Hyundai Santa Fe Sport. The contact stated that while driving at 60 MPH, the vehicle independently downshifted without warning. The vehicle continued to hesitate upon depression of the accelerator as the vehicle failed to accelerate above 30 MPH. Due to the failure, the contact had the vehicle towed to the dealer where she was informed that the vehicle needed a long block and turbo replacement. The manufacturer had yet to be notified of the failure. The vehicle had yet to be repaired. The failure mileage was 64,000.