I was on my way back home from Alexandria LA on [XXX] when I heard like the sound of an blow out tire but wasn-??t happen to look in back of car and seen back seat was blown off the area of the car and proceeded to see that the gas tank was expanded like you would see a balloon and the me car started running funny and. Then a service code comes across the screen of the radio po45100, so I pull over and look beneath the car and see that the gas tank is so expanded it-??s now pressing against the exhaust pipe. So I turned car off and here we are now I-??m without a car due to this. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

- Anacoco, LA, USA

A week before my gas tank expanding I heard a loud popping noise. When driving from NC to DC, my gas tank refused to take gas and my car immediately went to empty. I was stranding on the highway and has my 2020 Hyundai towed to the Hyundai dealership in Chesterfield, VA. They told me that my gas tank expanded and my back seats had popped out of place.

- Laurel0, MD, USA

It looks like the fuel tank has expanded. My back seats are now lifted & will not push down.

- Dallas , TX, USA

Driving 55mph on highway car slows down and make a pop nose and back seat comes up and I start to smell gas

- Memphis, TN, USA

I have a 2020 Hyundai Sonata SEL Plus. For the past month I been dealing with my CEL regarding Fuel Tank Pressure sensor and I end up replacing one from hyundai itself. After doing that I notice my fuel tank has expanded and I-??m currently dealing with Hyundai & the dealership to see if they can make a recall regarding this issue or just fix it period since it-??s a big safety concern. This been happening since mid April. My back seat lifts up from time to time and my fuel pump cover is bent. Below I-??ll add some pictures so you guys can see how my tank straps are actually bent which is very uncommon for it to happen. I recently took it to the dealer last week after reaching out to hyundai corporate and they took pictures and send it for prior approval to see if hyundai is willing to replace this. I can-??t fill up my gas tank, I constantly have to out between $15-$25 the most due to fuel mileage issue since the tank has expanded I get fuel mileage inconsistency

- Ocala, FL, USA

An independent service center advise us that the gas tank had expanded which could have put my family at risk if exploding or catched on fired. This happend on June 15th 2024 while driving, a sudden explosion coming from the back of the car was heard. Little after the explosion like sound we perceived as if air was coming through the back as if we had a window rolled down. When pulled to check, i notice that the back seat was popped up. No warning on the car was giving prior to the incident. Will take car to Hyundai dealership to have it inspect by them and have a solution.

- Somerton, AZ, USA

I was driving on the interstate when I heard a click from the back of the car. The gas gauge started to move downward as if I was losing gasoline. It eventually stopped and started moving back up, past where it was when it started decreasing. A little bit later the check engine light came on and the car started driving very sluggishly. I took the car into the Hyundai dealer and they found that the backseat was clicked out of place and a sensor was unplugged. This issue has since occurred multiple times. The back seat will pop out of place, the gas gauge will move beyond the gas that is in the tank, and finally the check engine light will come on and reduce the performance of the vehicle. The gas tank appears to be swelling and pushing up against the back seat which is causing it to pop. I had my girlfriend drive the car while I sat in the backseat and I could actually feeling something moving underneath the backseat. I have since gotten in contact with other sonata owners who have had the same thing happen with their vehicles. In other cases the backseat has exploded and flown completely off of the gas tank. I am very nervous to drive my car and think Hyundai should recall these vehicles before someone gets hurt.

- Temple Terrace, FL, USA

Summary: The gas tank on this vehicle blew up/expanded rapidly to the point it could have erupted into a gasoline vapor fireball, killing the occupants of the vehicle or others. According to two Hyundai dealers, a failure in a check valve and the vehicle ECU programming caused pressurized air from the engine to be pumped into the gas tank, causing it to expand to the point of explosively popping out all of the sheet metal under the back seat. One Hyundai dealer service technician described the vehicle as, quote, 'a ticking time bomb'. There was no check engine light or warning at the time of this explosive event, although one occurred later. Hyundai has not offered to repair this vehicle. Please note that this potentially deadly issue is already well known to Hyundai/Kia. The Sonata has a sister vehicle from Kia that is the same vehicle platform called the K5. Kia issued a service campaign to address this extremely dangerous issue in April (TSB: SC288 K5 (DL3a) April 2024) which reads in part: "The subject vehicles may experience fuel tank swelling due to an issue with the PCSV check valve, which results in pressurized air to flow into the fuel tank." In addition, at last check an investigative reporter in Charlotte, NC has identified numerous Hyundai and Kia vehicles in which this has occurred. There's likely far more people who have already had this occur, and potentially thousands or hundreds of thousands of vehicles with this potentially deadly condition. (See: wsoctv.***/news/local/kia-acknowledges-gas-tanks-swelling-suddenly-offers-free-fix) As stated above, Hyundai has not offered to fix my vehicle. Please immediately take steps to force the manufacturer to remedy this extremely dangerous condition for all affected owners before someone is injured or killed.

- Tampa, FL, USA

The fuel tank under the backseat expanded forcing the backseat up and causing the muffler to scrape the ground. The expansion of the fuel tank could have exploded due to extreme pressure. Vandergriff Hyundai in Arlington, TX has inspected the vehicle and confirmed component failures in the fuel system. The vehicle has been inspected and currently in the process of being repaired at the dealership. The check engine light was illuminated to warn of component failures approximately six weeks ago.

- Glenn Heights, TX, USA

While driving at about 45mph a warning flashed on my dash. I couldn't read it before it disappeared, but it was something about front collision., contact dealer. the car immediately lost all power. Everything was still running, but I had no acceleration. I had to back down a busy road into a vacant lot. I had just come off of the highway when this happened, if I had still been driving on the Highway, I would have been hit by a car from behind, since there was no warning at all. The car was towed to a Hyundai dealership. After a diagnosis, it was said to be the Throttle body. I had to wait for the repair because the part was on back order. I was told that there was another car there waiting on the same part. I am afraid to drive the car now, even though the repair was made. I feel this is a safety hazard, and that someone could be injured or killed because of this issue with the car.

- Cottonwood, CA, USA

As the vehicle was at a complete stop and waiting for a chance to get in traffic, the car hestiated and would not respond to the depress of the gas pedal, for a second or two... very strange indeed!....is it a transmission issue or something else....the transmission shifts strange from the complete stop position...this happenes more than once! and one instance it actually jerked ( bucked) somehow...concerned about this...

- Sharon, MA, USA