2017 Hyundai Santa Fe Sport: misfire or rough idle

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 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 Oct 3, 2025 · Engine · TN

On [XXX, I was driving on the interstate when my engine seized and the car lost all power, leaving me stranded on the side of the road on a busy exit at night. This was very dangerous to myself and others. I purchased this car in July of 2023 with 69,000 miles in good condition. I immediately made an appointment to take care of the recalls and updates to this car, which were performed February 2024 due to this being the first available appointment. Also, at my first oil change (3,000 miles after the previous oil change) I was told by the mechanic that there was absolutely no oil in my car. Since then I have had to put SEVERAL quarts of oil in between each oil change, costing me hundreds of dollars. Then June of 2024, the P1326 code flashed on my car and it went into limp mode also while I was driving on a busy street, putting myself and others in danger. I took it to the dealership and was advised to continue driving it and there was nothing they can do until my engine fails. I also brought up the oil consumption issue and was told that even if I did an oil consumption test (at my cost), there was nothing they could do. I was advised by my service advisor not to do a consumption test. I took his advice and continued to drive my car, adding countless quarts of oil weekly to my car. Fast forward to September 2024, when my engine light came on due to misfires in cylinder 3&4 and I took it to a local mechanic due to the incredibly long wait for an appointment at Hyundai. I was told all 4 spark plugs were oil fouled due to excessive oil consumption. This happened again July of 2025. My mechanic advised me that there was nothing to do about it, but that this would continue to happen due to the oil consumption issue. Now Hyundai is refusing to take responsibility for this engine that has had documented issues resulting in class action lawsuits and safety issues for myself and others and refusing any financial assistance. No warning lamps were on before incident. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATIO

Filed Sep 28, 2025 · Engine · CT

On [XXX], around [XXX] I was driving my car on [XXX] and I suddenly experienced "Check Engine Flashing" and engine misfiring. I was driving ~70-75 mph in the left lane. I immediately turned ON the Hazard lights and somehow manage to get to the right lane and safely stopped the car in open space on the side. This could have resulted in a very serious accident as I had my whole family in the car with me. Hyundai Motor Company must be held accountable for this type of engine quality issue. My car has 119580 miles. I had always car maintenance done at Hyundai Dealerships to make sure that it is maintained as per the company recommended. The Catalytic converter in my car was changed by the Hyundai Dealership (Key Hyundai Manchester, CT) at approximately 96000 miles as it had gone bad in April of 2024. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Jul 28, 2025 · Engine · FL

Bought my vehicle as second owner and 1 1/2 years into financing I discovered the piston rings are failing which is causing to much oil consumption. It’s burning oil to fast - in three weeks my car has burned through three quarts of oil. I do my regular oil changes as recommended and already change the gasket. If I have not checked my oil I would never had a clue. I am currently doing my oil changes because the dealer shops were not nor even knew of the burning oil issue. How does one car burn that much oil in three weeks. My extended warranty has exited and now my engine is failing. My vehicle was not included in the class action settlement. I am a teacher with children and don’t have the money to buy a new car let alone fix the engine. The vehicle has rough idling at times and doesn’t have the power to go sometimes. It’s failing quicker than I could imagine.

Filed Feb 7, 2025 · Engine · CT

On December 28th, 2024 I was driving my SUV on the highway at highway speeds. I bought the suv from a Manchester Acura dealer on November 9, 2024. I am the second owner. While driving, the check engine light came on. I was able to complete my drive, but the car idled very rough. After getting the car home, my father checked the oil. It did not register on the dip stick. He put in about two quarts of oil. The check engine code was P0302, which is misfire in cylinder two. He proactively changed the spark plugs since the car had 92,000 miles on it. After changing the plugs, the code did not clear and the engine continued to idle rough. He did a compression test and confirmed that cylinder two had less than 50psi compression vs the other 3 cylinders which were at 170 psi. He also removed and inspected the new plugs after running the engine and cylinder 2 plug was already dark and oily whereas the other plugs were in as new condition. I opened a case with Hyundai Care America. They instructed me to take the suv to a Hyundai dealer for diagnosis. The verbal report of that diagnosis was burnt valves on cylinder two. The dealer stated that HCA would not cover a repair or engine replacement. Hyundai forums and NHSTA complaints are numerous around high oil consumption and burnt valves on Theta II engines. Hyundai needs to be held accountable.

Filed Jul 3, 2023 · Engine · 104,000 miles · TX

The contact owns a 2017 Hyundai Santa Fe Sport. The contact stated while driving 60 MPH, the vehicle lost motive power and the check engine warning light illuminated. The contact was able to pull over into a gas station where the vehicle started shaking and lost motive power and stalled. After several attempts the contact was able to restart the vehicle. The vehicle was taken to an independent mechanic and stated that the #3 spark plug was misfiring and needed to be replaced. The vehicle was repaired but the failure recurred several times. The vehicle was taken to another independent mechanic and stated that the engine needed to be replaced. The dealer was contacted but no assistance was provided. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was 104,000.

Filed Jan 10, 2023 · Engine · 110,000 miles · OK

The contact owns a 2017 Hyundai Santa Fe Sport. The contact stated that the vehicle stalled while idling with the check engine warning light illuminated. The contact had taken the vehicle to a dealer to be diagnosed. The mechanic determined that cylinder #4 misfired, leading to engine failure. The contact attempted to reach the manufacturer, but his calls were not answered. The vehicle was not repaired and remained in the possession of the dealer. The failure mileage was approximately 110,000.

Filed Jan 8, 2023 · Engine · TN

Engine burns over 10th of oil every 5000 miles. Also has a constant check engine light due to misfire on 4th cylinder

Filed Dec 14, 2022 · Engine · UT

Engine was consuming oil badly. Engine has 98000 miles on it. Then driving one day, lost most power. So I got it home and ran codes and was having multiple cylinder misfire. Had it towed into dealership, and then did a diagnostic and claimed there is bad cylinder head damage and I would need a whole new engine. Which they said would not be covered under warranty. Which seems odd since these engines have a lifetime warranty because of a class action lawsuit. So I started a case with hyundai corporate, and they said they weren't going to cover it under their 5 year 60k warranty. But that isn't the warranty that should cover it. So, I am in the process of having the BBB dispute this for me. Because I cannot afford the huge amount to have them put a new engine in. This has been the biggest pain and I have been out a car for months with no loaner or anything.

Filed Oct 6, 2022 · Engine · 108,000 miles · CO

The contact owns a 2017 Hyundai Santa Fe Sport. The contact stated that the dealer had previously performed Service Campaign: 953 (ECM & Cluster Update-Engine Monitoring Logic Product Improvement) however, the failure occurred after the service campaign was performed. The contact stated while driving 75 MPH, the vehicle went into Limp Mode. The vehicle was towed to the dealer, and the dealer replaced the engine; however, the failure recurred, causing the vehicle to shake violently while driving with the check engine warning light illuminated. The vehicle was towed back to the dealer; however, the dealer was unable to duplicate the failure. The dealer determined that the engine had misfired. The vehicle was not repaired. The manufacturer was made aware of the failure and a case was opened. The failure mileage was approximately 108,000.