Hyundai Santa Fe Sport misfire problems

Filed Nov 2, 2026 · Engine · GA

On XXXX, my 2016 Hyundai Santa Fe Sport AWD (VIN [XXX], ~89,151 miles) developed a flashing check-engine light while driving — an active misfire condition. An OBD-II scan pulled code P1326, Hyundai's knock-sensor detection code for connecting-rod bearing wear in the Theta II engine family, the same defect family covered by Hyundai's lifetime bearing-warranty extension under Service Campaign T6G (TSB 22-01-023H-1). The vehicle was towed to Grand Hyundai of Canton (repair order #XXX). The dealer performed the bearing clearance test (BCT, TSB 21-EM-004H-1) on XXX, and recorded only "PASS." The printed result from the dealer's own GDS diagnostic tablet shows PASS with no numerical clearance values, even though this is a measurement-based test. The knock sensor was NOT replaced, and a KSDS software update was performed. The final invoice was $0. I have asked, in writing and repeatedly, for the actual numerical clearance measurements from that test. I have not received them. What I have received instead is a contradiction: On XXX, at vehicle pickup, the dealership's service manager told my wife, [XXX], that the dealership does not have access to those results and that only Corporate has those measurement results. When she asked him to put that statement in the service notes, he refused — "we will not put that in the notes" / "she could not write it down." Service advisor [XXX] was present beside the manager, relayed the request to him, and relayed the refusal back; she witnessed both the statement and the refusal. The same manager had told me by phone that only Hyundai Corporate has the measurements. On XXX, Hyundai National Consumer Affairs Supervisor [XXX] wrote the opposite: that "diagnostic, testing and reporting results done by the dealerships are retained by the independent location" and only the servicing dealership can provide them. She refused to provide the numbers herself and said INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Jul 22, 2026 · Engine, Fuel system · TX

We have a 2017 Hyundai Santa Fe Sport with a refurbished engine due to a past class act settlement, we were notified by Hyundai to bring in the vehicle for Service campaign 9C2 to update the Engine Control Module (ECM) Software for vehicles equipped with the (2.4 GDI) Theta II refurbished engine, which we have. The morning after we updated the 9C2 software, after starting our car cold for the first time in the am, our car went into limp mode, shaking very badly, it would not accelerate above 20 MPH, it had a lot of trouble shifting from 1st to 3rd gear and acted like it was going to stall out and then die in the middle of the road while I was in the car with my 2 children. The dealership we took it to was not able to duplicate the limp mode, but has documented that they did witness hesitation and sluggishness while test driving it. I cannot validate that it was test driven cold immediately as requested as all their test drives were done without me. Due to the vehicle not accelerating as it should normally, I feel the vehicle is very unsafe and unreliable as well. I’m willing to provide more documentation, and our car is available for further inspection. I did request the help of a Hyundai customer relations case manager who stated Hyundai is aware of all of the drive-ability issues I have stated and he said they are hoping to provide another software update, but that time frame is unknown. Dealership mechanic stated the same thing and believes our issue is related to the 9C2 update. The manufacture has not inspected the vehicle, but we would absolutely love them to if they would. There have been no check engine lights come on before or after this update, only misfire codes came up after the update which dealership has those, and since the dealership was unable to witness it going into limp mode while driving it, they could not gain the much needed data that pinpoints the exact problem. We were advised to warm up car and rev up the RPM to above 2,000 before driving.

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 May 29, 2026 · Engine, Fuel system · SC

After the ECM recall for a software update the car would not run correctly. It jerks and and runs rough. It almost stalls when you put your foot on the gas. I took it back to the dealer and they can not get the problem to duplicate. Noone else has looked at the problem. There were never any problems with the care until the recall. The problem occurred the day I brought the car home from the ECM update.

Filed May 28, 2026 · Engine · NJ

Hello, I was driving home from work with my six-month old in the car and the engine stalled while on the Belleville Turnpike. It seized and I was almost rear-ended by a tractor trailer hauling lumber to the lumber yard just a few streets away. I couldn't move the car and was afraid of how to even attempt to secure my car as my daughter was strapped in her car seat. An extremely nice man pulled over and began to flag vehicle to go around me. By this time, I had only my hazard lights on. I was frightened beyond belief having gone through that experience. The car was towed to the dealership who confirmed it was catastrophic engine failure(misfire of a cylinder). They stated initially with my 3rd party warrant that it would be covered and in their words " it was a good thing I had a warranty". Fast forward to two weeks after I check to see what is going on. Things have changed. Now, because I am missing one oil change receipt, they need to be paid $1400, to further corroborate the cause of the engine failure. I haven't paid and honestly don't plan on paying them anything. To date, I have spent over $2,000 on car rental fees since my car is now sitting at the Global Hyundai Dealership.

Filed May 25, 2026 · Engine, Fuel system · KY

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.

Filed Apr 7, 2026 · Engine, Fuel system · TX

My 2018 Hyundai Santa Fe Sport equipped with a Theta II GDI engine began exhibiting excessive oil consumption, engine knocking, and cylinder misfires consistent with the known Theta II engine defect covered under the Hyundai class action settlement. Prior to the failure, the check engine light illuminated and I experienced repeated misfires and audible engine knocking. The vehicle required frequent oil additions between oil changes due to excessive consumption. The vehicle was taken to an authorized Hyundai dealership where a diagnosis confirmed a burnt valve inside the cylinder head. The dealership recommends replacement of the cylinder head or complete engine replacement to correct the issue. The dealership performed a bearing failure test and attributed the burnt valve to carbon buildup. However, excessive oil consumption in a GDI engine directly accelerates carbon buildup on intake valves, as burning oil deposits carbon on valve surfaces preventing proper seating and causing overheating and valve failure. The carbon buildup is therefore a consequential result of the Theta II oil consumption defect, not an independent cause. The safety risk is significant as engine misfires and knocking while driving create unpredictable loss of power and potential for stalling in traffic. The vehicle is currently not reliably operable. The manufacturer has been contacted regarding coverage under the Theta II settlement. The component is available for inspection upon request at the servicing dealership

Filed Apr 1, 2026 · Brakes, Electrical · KY

I was told by a mechanic that something electrical is wrong with the vehicle it causes the engine to misfire. Different issue than before.

Filed Mar 19, 2026 · Engine · IN

I drove 2.5 hours north to a Marine brother's father's funeral, who unexpectedly passed. I started my drive home and made it to Yorktown in about 15 minutes, and the engine light came on, started flashing, and went into limp mode. I pulled over on I-69 to shut it off, pulled the dipstick, and the oil level was full. I pushed the Bluelink button on my rearview mirror, and HMA sent a tow truck to tow the vehicle to a local dealership about 10-12 minutes away. The dealership did not inspect the vehicle until the following Monday, since it was Friday, three weeks ago. The dealership found DTC codes for misfires in cylinders 1 and 2, multiple-cylinder misfire, and too-high pressure in all four cylinders. The vehicle has had the knock sensor replaced, a KSDS ECM update, and a series of gaskets replaced. It has been burning oil since 69,362 miles and is now not operational, 2.5 hours from home. HMA has declined to replace the engine on a vehicle involved in a class action settlement due to problems with several completed replacements. The dealership has followed the manufacturer's process, and, due to the engine not producing a code it had at 87,986, but now not capable due to piston damage, cylinder scouring, and spark plug damage, the manufacturer has declined a goodwill replacement. The engine failure did put others in harm's way, as it did me when having to pull off the busy interstate to inspect the obvious failure. I have been driving a rental since this situation occurred, have a vehicle that is not operational, and a manufacturer that is not assuming responsibility for the catastrophic failure. I have read numerous forums across several platforms about the Theta 2 engines. The vehicle has been serviced as needed, including multiple requests to fix or repair the engine noises it produced, when the oil level became low, and oil had to be added.

Filed Mar 18, 2026 · Engine · FL

I am reporting a serious safety concern involving a 2018 Hyundai Santa Fe Sport with approximately 132K miles. While driving at highway speed, the vehicle suddenly lost power/velocity and the engine light flashed. This created an immediate safety hazard, as maintaining speed is critical in highway traffic. Within seconds, the vehicle regained power and the warning light turned off, giving the impression that the issue had resolved. Shortly afterward, while exiting the highway, the vehicle began shaking and felt as though it would stall but was able to drive home less than one mile. A mechanic retrieved misfire codes for cylinders 2 and 4. Further inspection revealed internal engine damage in cylinder 4 requiring major rebuild. A full deconstruction revealed that one of the valves in cylinder 4 had partially broken. This failure occurred with little to no warning and involved a sudden loss of power at highway speed, which could have resulted in a serious accident. The vehicle’s warning systems did not provide adequate or persistent alerts prior to significant engine failure. Over the last 6 months it began consuming oil frequently requiring weekly checks, however no warning systems or errors to indicate an underlining concern. Based on research, similar Hyundai vehicles have documented issues involving excessive oil consumption and internal engine damage without sufficient warning. This raises concerns about a potential safety defect affecting engine performance and failure detection.