2017 Hyundai Santa Fe

Vehicle was brought to an authorized dealership for service, and while there Campaign 9C2 (ECU Software Update for Theta II Emissions Improvement) was performed. Immediately following this software update, the vehicle developed drivability degradation, specifically engine stutter/hesitation and rough transmission shifting during cold starts. When attempting to accelerate in the first few minutes of driving, the vehicle delays engagement and then suddenly surges or lurches forward unpredictably. This creates a safety hazard, as the unpredictable power delivery and lag prevent the vehicle from accelerating safely when merging into traffic or turning across oncoming lanes, placing occupants at an immediate risk of a collision. The software logic error is fully reproducible every time the vehicle has sat long enough to cool down. The dealership confirmed the update was applied. There were no warning lamps or symptoms prior to the 9C2 update; the failure was caused directly by the manufacturer's campaign software modification to the Engine Control Unit (ECU). The vehicle and its ECU are available for inspection upon request.

Known as an issue with Hyundai, but unresponsive to correct because no diagnostic code is sent. Transmission will shift extremely hard from 1st to 2nd gear randomly. In keeping track of the mileage, this appears to happen every 200 miles or so. Also, it faild to upshift correctly, making the entire car shudder. Also, at times it will not go into reverse gear. On one occasion, after finally doing so, it slammed so hard into reverse I almost collided with the car behind me.

My 2017 Hyundai Santa Fe, purchased new from Lynnes Hyundai in February 2017, has approximately 93,000 miles. The vehicle previously developed a significant oil-consumption/engine problem that was diagnosed by Hyundai, and Hyundai replaced the engine with a remanufactured engine. Approximately two weeks after the engine replacement, the check-engine light illuminated and DTC P1326 was identified. The dealership replaced the knock sensor. Approximately two weeks later, the check-engine light illuminated again with a recurring P1326 condition. The vehicle is currently at Lynnes Hyundai and has been there approximately three weeks while they attempt to determine the cause. Hyundai Techline is involved. Prior to the current repair visit, while traveling approximately 60 mph, the vehicle experienced a very forceful hesitation that jerked the vehicle. I immediately slowed down and pulled onto the shoulder. The vehicle continued to hesitate intermittently while I drove slowly to safety. I was concerned that the vehicle could lose power or shut down while I was driving at highway speed, creating a risk of a crash. The recurring P1326 condition has been confirmed by the Hyundai dealership. The vehicle and engine have been inspected by Hyundai/Lynnes Hyundai multiple times, including after the engine replacement. The current recurring condition has not been resolved. The check-engine light is the warning lamp associated with the current condition. I do not know the underlying cause of the recurring P1326 condition; Hyundai is currently attempting to diagnose it. The vehicle is currently available for inspection at Lynnes Hyundai.

Complete unmitigated loss of acceleration and power while traveling at highway speeds, creating an immediate life-threatening road hazard. Following a warranty engine replacement and mandatory dealer software flash at Clay Cooley Hyundai (Sherman, TX), the vehicle began experiencing powertrain communication issues. While operating the vehicle at 65 MPH on the highway, the vehicle completely failed to accelerate and lost propulsion power, nearly resulting in a catastrophic rear-end collision with an oncoming 18-wheeler semi-truck. Dealership diagnostics claim "no trouble codes present," but live data telemetry confirms the High-Pressure Fuel Pump (HPFP) is actively commanding and delivering a dangerous 1,600 PSI to the fuel rail at hot idle. This abnormal fuel delivery is paired with a severe powertrain stutter in 3rd gear. Service personnel at multiple locations confirm a widespread, high volume of transmission failures and severe drivability issues specifically tied to this recent Hyundai software update. Corporate has denied repair coverage. The vehicle remains an active highway safety hazard and is completely undrivable.

The contact owns a 2017 Hyundai Santa Fe. The contact stated that while reversing, the vehicle jerked and shuddered abnormally. Additionally, the transmission hesitated, and the vehicle almost stalled. No warning lights were illuminated. The vehicle was taken back to the dealer where the contact was informed that the Service Campaign Number: 9C2 was completed. The contact was informed that the updated software was confusing the transmission and had caused the failure. The contact was informed that the remedy was not yet determined. In addition, the contact was informed that the dealer was waiting on instructions from the manufacturer. The vehicle was not repaired. The manufacturer was made aware of the failure but provided no assistance. The failure mileage was approximately 63,036.

The 2017 Hyundai Santa Fe was brought to dealership on 3/27/26 for an oil change and a computer update was completed for Emissions Improvement. Upon picking the vehicle up after service, it was noticeable that it was not shifting correctly. I spoke to the service department and asked if the memory was cleared with the update an if it was having to relearn how I drive and the said it should not be affected. This went on for a few days and I left the car with them to duplicate as there were3 no stored codes. After a few weeks, the Teck Line recommended a new transmission, which Hyundai offered goodwill assistance. As we were waiting for the transmission to arrive from being on backorder, a bulletin for Service Campaign 9C2 was release on 5/18/26 that described my experience with shifting issue almost exactly. The transmission was replaced and the drivability issues still persist. Hyundai says that I must let my car warm up for 1-3 minutes to allow a catalyst to reach temperature and not cause rough shifting. This rough shifting is the effect of the update and thus te reason that my transmission needed to be replaced. Further investigation showed that this update is a known issue and cannot be reversed once installed. Currently, I must start my car in 90 degree weather to warm it up as a result of this update which is not logical in any thought process. I have asked Hyundai to cover the balance of the new transmission as this is a result of thier faulty software update with no success.

A Hyundai recall 9C2 update was applied to my vehicle. Ever since that update my vehicle hard shifts on cold starts which I fear is damaging the transmission. Hyundai dealer was able to replicate this and keeps advising us that concern is ‘under review with Hyundai’. I have the service order that states this. This problem has been ongoing for Months! I think Hyundai needs to find a resolution to this as my research indicates it is impacting a lot of customers.

My 2017 Hyundai Santa Fe (VIN: [XXX]) was brought to Herb Chambers Hyundai of [XXX], in December 2023 to address the Underbody Corrosion Recall/Campaign (9A0). The dealer performed the preventative service. However, the remedy completely failed because the frame was already severely structurally compromised by rust. In early 2024, I relocated to [XXX] with the vehicle. Now 2026, The front subframe sub-assembly deteriorated to a hazardous point, forcing me to spend a large sum of my own money on front-end repairs caused directly by this corrosion. Currently, the rear subframe and rear suspension components are heavily corroded and structurally disintegrated. The vehicle is completely unsafe to drive, presenting an imminent risk of structural collapse and suspension failure while in motion. Hyundai's recall remedy was ineffective and merely masked the rust. The rear subframe (crossmember/cradle) and control arm anchor points are severely corroded, rusted out, and crumbling to the touch, creating an imminent risk of suspension collapse while driving. The extreme corrosion has spread to the metal fuel line the vehicle is unsafe to drive due to the advanced corrosion . Denial of Service by Local Distributor: The vehicle is currently located in the U.S. territory of Puerto Rico. I presented the vehicle and documentation to the local authorized distributor, Sojitz de Puerto Rico (Hyundai of Puerto Rico). As indicated I brought the Vehicle to MVP Hyundai Humacao (XXX) and filed a claim (# XXX) However they never sent a anyone to inspect the vehicle or process a safety claim, claiming they bear no responsibility because the vehicle was imported from the mainland, Because this is a failed federal safety campaign remedy that now poses an immediate threat to my life and public safety, INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The vehicle is in limp mode and is displaying a flashing check engine light with a P1326 powertrain code. The vehicle in question is a 2017 Hyundai Santa Fe Sport equipped with a Theta II 2.4L GDI engine at 118,000 miles. Per the service campaign T3G, listed on the NHTSA website, this vehicle is covered under warranty repair since it is a Theta II engine vehicle that is displaying an active P1326 power train code. The vehicle is under he 10 Year/120,000 miles limitations of the extended warranty. The dealer just submitted to us a quote to repair the vehicle and is stating that none of the repairs listed are covered under warranty. This includes a quote to replace the engine knock sensor, which is a warranty item under the T3G service campaign’s extended warranty.