Hyundai Sonata won't shift problems

Filed Oct 17, 2026 · Transmission · NC

Transmission problems began around 60,000 miles (but we didn’t know what it was) — jerking and hesitation, that worsened over time. We took the vehicle in (November 2025 ),at around 109,000 miles at which time they couldn’t find anything. I took it back in December and they recommended the spark plugs. We took the car back again in March at which time they recommended other little things. We took the vehicle back yet again on March 10 and told them to check the transmission. The dealership said “ As far as the transmission, we cant get it to really do anything so if you dont have an extended warranty we would recommend waiting until the issue gets worse and then put a transmission in it unless you wanted me to get you a price on it”. The vehicle has been at an authorized Hyundai dealership since the third week in June 2026 (because I wanted them to tell me why I had a bad transmission in my three year-old car) while awaiting resolution from manufacturer's consumer advocate (they took 60 days to resolve absolutely nothing). A replacement transmission was authorized on August 6. The manufacturer-supplied replacement was installed and found defective on August 27 (when I asked to test drive the car with a mechanic) it would not shift past 3rd gear. When I asked the dealer why I was not informed, prior to my picking up the vehicle, he told me “we don’t tell the consumer every little thing”. A second replacement was supposedly ordered from the manufacturer August 27, and is still not installed as of October 17. The manufacturer told me “the part was in and being worked on” 10/2. This was false. Th dealership is holding my vehicle hostage and demanding $5,786 for the defective replacement. My vehicle cannot be retrieved. The original transmission that was jerking and hesitating was a hazard to myself and other drivers around me, especially on the highway. The dealer even told me “ this is the third defective manufacturer replacement part received this month”.

Filed Oct 15, 2026 · Brakes, Engine · KY

Vehicle experienced intermittent, severe powertrain defect resulting in a critical safety hazard. Between 30K and 36K miles, the vehicle underwent 3 violent highway deceleration episodes. During these events, the engine began shaking, escalating to violent shaking; with deceleration and coming to a stop, it would shake, then sputter as if it would die. Coming to a complete stop, a total stall was prevented only by the ECM forcing a limp mode lock at 1200 RPMs. When Auto Hold was engaged at this point and my foot was removed from the brake pedal, the mechanical surge caused the vehicle to unexpectedly lurch forward, fighting against and nearly overriding the factory Auto Hold braking safety feature before finally holding. Luckily, no pedestrian was walking in front of my car when this occurred. No check engine light (CEL) or dashboard warning ever illuminated. This safety compromise is directly tied to an ineffective or adjacent remedy involving Service Campaign 9B1 (Opcode 40D219R0) and Safety Recall 286. Under this Opcode, a factory software flash deleted the standard OBD-II trouble code P0451and substituted it with a manufacturer-specific shadow code P14EE00. This software manipulation suppressed universal emission/pressure sensor faults, masking a volatile physical defect within the high pressure fuel delivery and ignition systems. Dealer diagnostics on a running, compromised engine flagged an improper fuel injector pulse and subsequently a failing Cylinder 3 ignition coil. All four injectors were replaced but only one coil, leaving 3 non-updated , factory defective coils in the engine. The vehicle remains an ongoing highway stalling and brake-override hazard due to an incomplete field remedy of a recall-adjacent system. I've filed a Hyundai Complaint with assigned case number 43394228 regarding Safety Recall 286. (Two episodes of the attempted Auto Hold override occurred - first 09/09/2026 and second 09/29/2026.)

Filed Oct 5, 2026 · Engine · UT

I was driving on the freeway about 100 miles outside of Boise, ID when the vehicle went into limp mode and a flashing check engine light came on. I had it towed to the Hyundai dealership in Boise where they ran a diagnostic check and it came back with a P1326 code, which is the issue related to the engine/ball bearings. They said it passed the bearing clearance test (BCT) so they updated the software and gave the car back. I picked it up a week later and while driving it from Boise to Salt Lake City (where I live), it went into limp mode again with a flashing check engine light. This happened about 100 miles north of Salt Lake City. I had it towed to a dealership in Murray. They indicated it passed the BCT again, but they replaced the knock sensor and did an oil change and gave the car back. I picked it up, and the next day, while on the freeway, the same thing happened again. I took it back to the dealership. They indicated the knock sensors they just installed the day before needed to be updated, so they updated the software for the knock sensors. I just picked it up, and within 45 seconds of being on the freeway, it went right back into limp mode with the flashing check engine light. This has happened 4 times now, on the freeway forcing me to immediately get over, and I have almost gotten into two separate accidents because of this. Hyundai says they will not replace the engine because it keeps passing the BCT. The vehicle is not safe to drive and it is likely causing irreparable damage to the other systems of the car.

Filed Oct 4, 2026 · Engine · UT

While driving on the freeway, the check engine light started flashing and the gas pedal became useless. This put the driver and the passenger of the car in massive danger as they could no longer accelerate on the freeway. Luckily, they were able to get off the freeway without causing an accident. Upon reading the code at an auto shop, they discovered that it was P1326 or a knock sensor issue. This malfunction caused the car to go into limp mode and put the passengers in serious danger. Several calls to the Hyundai Service Center were made yesterday (Saturday, October 3rd). However, not one was ever answered. They hope to be able to get the car to the dealership's service center as soon as possible, but the earliest appointment online is multiple weeks away. This same car was recently at the dealership service center for an internal engine oil consumption problem and thoroughly inspected. The car is up to date on all software and recalls. Even though a valve cover replacement fixed the oil consumption issue, the owners are now having even worse issues. This is the only car for a married couple who are both working and going to college full-time. This issue has been a severe complication to their scheduling, and they were put in harm's way on the freeway.

Filed Sep 10, 2026 · Engine · 90,000 miles · IL

The contact owns a 2019 Hyundai Sonata. The contact stated that while driving 55 MPH, the check engine warning light illuminated, and the vehicle went into LIMP Mode. The contact stated that the vehicle failed to accelerate above 58 MPH. The contact retrieved DTC: P1326 (Knock Sensor Detection System) at O'Reilly Auto Parts and stated that the knock sensor had previously been replaced. The failure mileage was approximately 90,000.

Filed Sep 9, 2026 · Engine · FL

Knock sensor has detected a failure. Check engine light is flashing and the car is in limp mode.

Filed Aug 6, 2026 · Electrical, Fuel system · MA

1.) Following Hyundai's 9C2 Campaign update for the ECU that was completed back on May 27th, 2026, my 2015 Sonata went into limp mode [solid check engine light present] while I was accelerating up an on-ramp on the 2nd drive cycle since the update was performed. I was already far away from the dealership so I was forced to limp it to my local shop that I regularly use to have it checked out. It was confirmed that the code on the vehicle was P200A for intake manifold runners. Since the update was for smog regulation, the code was cleared in order to see if it would come back. Since then, it has not, however the vehicle continues to have one persistent problem. The RPMs will dramatically dip and then surge back upwards while the car is coasting (no gas and no brake applied). 70% of the time, you can feel the car violently jerk as it appears to try and correct itself. 2.) I've brought this car to multiple dealerships, have a case open with corporate and have also found that this is a systemic issue with this specific update in these cars. All and all, nothing has been done. I'm repeatedly turned away over and over again because their techs are only permitted to look into it once they have hard evidence of a fault. In this case, that would be a dashboard light. I'm told that I may only return if the check engine light comes back, which as I mentioned previously, posed a HUGE safety risk to myself the first time it appeared. If I can only go 55mph down the highway, I am at risk of being rear-ended or struck in some way. 3.) The problem has not been reproduced by the dealer as they will not test drive it to see the dip and spike. However, the code was still pending for awhile in the vehicle before it cleared it on its own, so that was acknowledged by at least one place. 4.) Vehicle has not been inspected by anyone but a dealership and local mechanic. 5.) No other signs prior to the vehicle limping out on me other than some acceleration concerns on May 27th, 2026.

Filed Aug 1, 2026 · Engine · AZ

This vehicle is subject to a known Theta II connecting rod bearing defect (Recall 162 / KSDS) and a related class action settlement. On October 2, 2025, the vehicle stalled while entering the highway. It was taken to Ken Garff Hyundai Surprise, and the following day, October 3, 2025, it entered engine protection mode (limp mode) during the dealership's own test drive, the exact behavior the Knock Sensor Detection System is designed to trigger for connecting rod bearing wear. The dealership's own service advisor documented in writing, as early as December 27, 2025, that he did not like how the vehicle ran and drove and wanted to resubmit a warranty claim. Despite this documented concern, on May 5, 2026, the dealership's service manager told Hyundai corporate that nothing was wrong with the vehicle and that it could be picked up. Hyundai corporate maintained that the engine had passed bearing clearance testing on two occasions, October 3, 2025 and May 23, 2026. I was told the vehicle was safe and retrieved it on June 29, 2026, out of necessity after my family's other vehicle was totaled in an accident. Approximately ten days later, the engine failed completely while I was driving with my family in the vehicle. Hyundai's own repair order documented the crankshaft as seized at over 95 lb-ft of torque. Hyundai subsequently approved and completed a full engine replacement. I am filing this report because a vehicle with a documented, known defect and a documented internal safety concern was represented to me as safe to drive, and it failed catastrophically with my family inside it within days of that representation

Filed Aug 1, 2026 · Engine, Transmission · LA

Going down the road driving the car lost power and went in limp mode with no warnings on the dash at all!

Filed Jul 8, 2026 · Engine · MN

My 2016 Hyundai Sonata 2.4L suffered an in-transit engine failure and entered emergency limp mode with an active P1326 rod bearing defect code, which is a recognized fire and safety hazard under the federal safety agency mandates. Service Campaign 953 was successfully completed on August 12, 2019, qualifying the vehicle for a lifetime settlement engine replacement. Walser Hyundai Brooklyn Park (RO #257457) has issued an administrative denial based solely on a prior-salvage title flag from a cosmetic theft recovery. The manufacturer is actively stalling a court-ordered federal safety recall remedy based on an administrative title brand, despite the engine compartment being structurally original and undamaged. Hyundai Corporate Case #42869828 is open but unresolved.