2018 Hyundai Santa Fe Sport

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)

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?

The engine on this vehicle suffers from a severe oil consumption defect that was first officially reported to the authorized dealership on February 3, 2025 at approximately 90,000 miles while under the factory powertrain warranty. The vehicle completely empties its engine oil supply in under 1,000 miles of normal driving. Running entirely out of oil within such a short interval poses an imminent, extreme risk of sudden engine seizure, catastrophic mechanical failure, and sudden stalling at highway speeds. The manufacturer and dealership have physically documented this rapid depletion of oil over a 17-month period but are refusing to replace the defective components, instead attempting to force this unsafe vehicle back onto public roads for repetitive driving tests.

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.

The contact owns a 2018 Hyundai Santa Fe Sport. While the contact’s daughter was driving approximately 10 MPH, the vehicle started bucking and shaking abnormally. The warning light indicating that the oil level was low had flashed on the screen. The driver pulled over to the side of the road and waited for the contact to arrive on scene. The contact inspected the vehicle and became aware that the oil level was extremely low. The contact added oil to the engine, and the dipstick failed to indicate the oil level until there was a quart full. The vehicle was taken to a certified mechanic, who diagnosed the vehicle with engine failure and referred the contact to the dealer. While attempting to drive the vehicle at approximately 20 MPH with the hazard light flashing on the highway, the vehicle lost drive power. The contact was able to coast to the side of the road and waited for the vehicle to be towed. The vehicle was towed to the dealer, but the vehicle was not diagnosed or repaired. The contact stated that the failure had occurred after consistent oil changes, and the next oil change was not due for 11 days. The manufacturer was not made aware of the failure. The failure mileage was approximately 75,314.

I had my engine replaced in Nov 2024 due to excessive oil consumption. I was required to do an emissions update due to a recall on my car. Once the dealer did the update, it caused my check engine light to come on and now I need a new catalytic converter, which was all due to the excessive oil consumption. Hyundai dealer knows this but they are telling me I’m responsible for replacing it. It should be replaced by Hyundai not me. It was the issue with the engine.

2018 Hyundai Santa Fe Sport. Purchased January 2026 took to Oxmoor Hyundai Service Center March 2026. February 2026 began using oil at a measured rate of 700 miles per tank of oil. Used 3 full tanks of oil within the month of February. Oil lights and engine lights on and off and flashing during this time. March 8, 2026, engine light flashed and then stayed on continuously. Engine shook and stuttered and made a loud noise. Engine stalled while I was driving at 35-40 miles per hour. I was able to continue driving to my home with the stuttering and stalling. The next morning I drove it to the Oxmoor Hyundai Service Center. I told relayed the timeline of all symptoms I had experienced over the 2 month lifetime of my ownership. They did not attempt to reproduce the issue. They only entered "shakes in reverse" as the customer provided issue on the intake information. Service Center performed diagnostic, found cylinder misfires on cylinder 2 and cylinder 4. Replaced spark plugs to resolve Cylinder 2. Cylinder 4 continued to misfire. Used Borescope and found broken valve. They did not address the scoring on the cylinder of the valve. Recommended engine replacement. Advised it would not be covered under a warranty because the rod did not break. The oil consumption was proven with documentation from multiple Valvoline visits and the vertical scoring was present on the cylinder with the broken valve in the borescope photo. The Service Center refused to do a Boring Clearance Test or any other test that would prove the engine should be covered under an extended warranty or class action settlement. It wasn't until I reviewed HMA documents uploaded to the BBB Arbitration, that I realized that the information I initially gave to the Service Center of all the symptoms with timelines had not been entered into the system for diagnostic review by Techline. Arbitrator denied my claim under the theta settlement because the rod had not broken yet, BUT she said my engine was defective.

TOOK CAR TO DEALER TO HAVE OIL CHANGED ON APRIL 29, 2026 AND WAS TOLD THEY HAD ALSO PREFORMED A SOFTWARE UPDATE, SERVICE CAMPAIGN 9C2. EVERYTIME SINCE THAT DAY AFTER THE CAR HAS SET FOR A LITTLE WHILE AND THE CAR IS RESTARTED DRIVEN IT STALLS AND SURGES REALLY BAD SEVERAL TIMES LASTING FOR SEVERAL MINUTES. IT ALSO CAN DO THIS AT RANDOM AT ANYTIME BUT NOT CONSTANT LIKE IT DOES WHEN FIRST STARTED. THIS IS VERY DANGEREST FOR OBVIOUS RASONS AND NEEDS TO BE FIXED. ALTHOUGH THERE IS OTHERS REPORTING THE SAME PROBLEMS ON LINE AND A PERSON MAKING THE SAME COMPLAINT WHILE I WAS WATING AT THE DEALERSHIP. THEY SAY "THEY ARE UNAWARE OF THE PROBLEM AND I WILL HAVE TO LEAVE MY CAR FOR UP TO THREE DAYS OR MORE TO HAVE IT CHECKED OUT AND THEN THEY WILL LET ME KNOW WHAT NEEDS TO BE DONE” AND WHAT THE COST WILL BE. I ONLY HAVE THE ONE VEHICLE AND THEY WOULD NOT PROVIDE A LOANER VEHICLE SO NEEDING MY CAR EVERY DAY I CAN NOT DO WITHOUT IT. DUE TO THE FACT THAT HYUNDAI REFUSES TO ACKNOWLAGE THE PROBLEM. THERE REALLY NEEDS TO BE A RECALL TO HAVE THIS PROBLEM FIXED.