2017 Hyundai Santa Fe Sport power train problems

“After we had the Hyundai 9C2 recall completed a few weeks ago, we immediately had rough shifting in our Hyundai Santa Fe Sport driving off the lot. Problem has continued since, and is most notable after cold start/once the car has sat for an extended period of time. Hyundai has released a Drivability Information on 5/18/26 regarding the known issue, but our Dealership was unaware. The Dealership recommended replacement of the Transmission, despite my explanation that the issue began after the installation of the recall fix.”

“This is in reference to the Hyundai 9C2 ECU software update for Theta II engines that have caused my 2017 Santa Fe Sport to hesitate, surge and run poorly the first few minutes after a cold start! I contacted my dealership but they have not offered any resolution as of yet even though Hyundai Corporate is well aware of the problems caused by the 9C2 software upgrade!”

“My 2017 Hyundai Santa Fe Sport exhibits a documented mechanical failure under active code P0420 (Catalytic Converter Efficiency Below Threshold). This failure is the direct proximate consequence of a severe, long term manufacturing defect in the Theta II engine block, which has caused excessive oil consumption. Following the official 1,000 - mile diagnostic driving protocol completed on XXX, Keffer Hyundai (a Hyundai dealer located in [XXX]) service department officially confirmed the active code P0420 catalytic converter failure. They issued a formal written recommendation to replace the entire engine assembly but generated an out-of-pocket consumer estimate of 10,035. This case falls under the the terms of the Theta II Class Action Settlement which requires Hyundai to cover the defective engine block under the Lifetime Warranty Extension, along with any subsequent component damage (the Catalytic Converter) destroyed as a direct result of the engine's oil burning defect under the Lifetime Warranty Extension.”

“Campaign 9C2 was installed on this vehicle and the now the vehicle is a danger to drive. My wife refuses to drive it as it bucks and jerks as well as the gas mileage has decreased from 35 highway to 28 highway. The fuel trims are way off on cold starts and the transmission now searches for the correct gear. Shifting back and forth. Just a slight touch of the accelerator and the car seems to jump forward which makes stop and go driving almost impossible.”

“Following the completion of an official emissions recall software upgrade at Fitzgerald Auto Mall Countryside, Clearwater Florida, my 2017 Hyundai Santa Fe Sport (52,000 miles) now suffers from a severe loss of motive power and erratic transmission shifting/jerking during cold starts throughout day. The vehicle continues to hesitate during cold starts, making it impossible to safely accelerate from a stop into incoming traffic. I returned to dealership on 5/29/26 to address continued driving issues. The servicing dealership states they don't have a software fix and offer no mechanical fix. The dealership states they received an internal memo from Hyundai Corporate which instructed the dealership to tell affected owners to idle the vehicle for 1-3 minutes before driving to allow system adjustments. Forcing a consumer to wait out a dangerous powertrain defect in a running vehicle to avoid a roadway acceleration/loss accident is an unacceptable safety hazard. The manufacturers recall update has actively compromised the safe operation and motive control of this vehicle.”

“COMPONENT FAILED: Theta II 2.4L GDI engine connecting rod bearings. Vehicle has 95,000 miles. Engine available for inspection in [XXX] . SAFETY RISK: Engine knock + limp mode at 1500 RPM caused sudden loss of power on highway. Oil consumption 1L/700km risks catastrophic engine seizure while driving. CONFIRMED BY DEALER: Independent service center confirmed DTC P0010 from metal debris. Hyundai Motor America Case #42623761 confirmed recall coverage but refuses remedy. INSPECTION: Manufacturer aware via Case #42623761. Local Hyundai dealers non-responsive. No police/insurance inspection. WARNING SYMPTOMS: Engine knock started at ~94,000 miles. Check Engine Light with DTC P0010. Progressive oil consumption. Limp mode activated at 95,000 miles. HYUNDAI VIOLATION: Hyundai confirmed via email they refuse to honor Safety Recall 162 / Service Campaign 966 Lifetime Warranty for VIN [XXX] despite all symptoms matching recall description. Request NHTSA compel Hyundai to authorize Bearing Clearance Test and engine replacement.”