2020 Hyundai Sonata FUEL/PROPULSION SYSTEM

I experienced an issue where the gas tank in my 2020 Sonata began to swell and emit loud popping noises while the vehicle was parked. I took it to the dealership, and Hyundai corporate eventually acknowledged the issue and agreed to buy out my loan. However, no official recall has been issued for this model year. This problem has had a major impact on my life. I lost my job due to not having transportation for over two months, and the stress of not knowing whether my vehicle was safe made it even worse. I had to upgrade my insurance for a loaner I never received, take financial hits, and go into deeper credit trouble—all while also recovering from a serious injury from a previous car accident. I now have to start over with a new loan while my credit is already damaged. I’m submitting this report not just for myself, but to ensure that other 2020 Sonata owners are protected and made aware of this issue. I believe this is a serious defect that warrants official investigation.

I received a notice in the mail my car needed a software update. I went to the dealership to have the update performed. They informed me there was a service campaign for an expanding fuel tank due to pressure. They were unable to return my car to me at that time stating they were awaiting direction from Hyundai Motor of America for the fix. The fuel tank expanded so much it bent the body of of the car underneath the backseat. It also broke the support straps. The dealership stated it was a known issue with a vent valve. Causing the fuel tank to swell so much it damaged the body. They have had my vehicle for 9 weeks with no direction as to what to next.

It was about 100 degrees outside yesterday, and while trying to pass a car, I look in my rearview mirror and notice there is fuel shooting out from my fill hose under my gas flap. I lost over 3 gallons of fuel on the road. This happened my whole 60 mile trip. This has happened to me before, but the temperature was around 76 degrees and it does not happen in cold weather. I have a feeling my fuel tank is expanding because when I took out my back seat where my fuel tank is located, the body of the car is all buckled up to the point where I can't get my backseat to latch down anymore. My car is available anytime for inspection upon request. I have not taken it to a dealer to get it looked at, there has not been a police report filed. And there were no warning lights or indicators other than a popping sound coming from my backseat area before the problem occurred. There are no warning lights or indicators after the problem either. I feel like I'm driving a bomb because my fuel tank could blow up at any time. This problem can be reproduced anytime by filling the tank and driving it in 90 degree weather.

Fuel system expanded back seat

Something went wrong in the fuel tank that caused it to become so pressurized that the tank expanded up and out so far that it pushed the exhaust pipe down and my back seat of out place. The only issue I had was the car was accelerating slower than usual but it wasn’t even enough of a difference for someone who didn’t drive it every day to be able to tell. It did this for two days then the check engine light came on and it just read “powertrain”. Began slow acceleration on 06.08.2025. Check engine light came on the night of 06.09.2025. I took it to the dealership 06.10.2025. I immediately took it into the dealership and they told me the car could have exploded. There was a previous recall for the fuel pump that I had replaced at the dealership. After seeing my car, they said their techs and the techs at HMA have never seen one this bad and that maybe after replacing the recall part the system update failed in my vehicle and the issue was never actually resolved.

What component or system failed or malfunctioned, and is it available for inspection upon request? The Fuel Tank expanded, was leaking gas from the gas tank opening. The expansion of the tank caused the metal plates/panel under the back seat to popup, where my child sits. Which caused a gap in the door. ir seepage from the back seat passenger door to where the fuel was leaking out the gas tank and also the fuel gauge on the dash was fluctuating. People on the highway was flagging me to let me know fuel was leaking. The fire department had to come and clear it. How was your safety or the safety of others put at risk? My child and I could have been seriously injured or killed. As well as people on the highway. It could have exploded. You can smell the gas in the car. The gas was coming out the gas tank on the side. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes, it was confirmed by Hyundai of North Charleston 8485 Rivers Avenue, North Charleston SC, 29406 and it was also checked by the insurance adjustor. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? It was inspected by the Insurance representatives State Farm Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? No I took it into the dealer and they said it was fixed and it did not fix the gas coming out the tank. And the same issue happened again on [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I took my vehicle in for an oil change and was advised that my car failed a recall. The PCV valve failed. After the dealership, explain this problem to me I no longer feel safe driving this vehicle. Imagine being told that the fuel tank can expand and pop up the backseat of your vehicle at any given moment or even cause the car to blow up and no warning lights coming on to alert you that this part had a defect.

The component that failed is the fuel tank system. While driving, the fuel tank expanded, causing significant damage to the rear section of the vehicle. This issue resulted in the rear seat rising up, and the bottom rear seat cushion detaching from its securing clamps. The check engine light came on, and gas started leaking from the fuel cap. The fuel tank has moved upward by about 3 to 5 inches, no longer resting on the factory fuel tank straps. The sheet metal underneath the rear seat was crumpled, and the fuel pump access cover bent. The vehicle is currently at College Park Hyundai and is available for inspection upon request. My safety and the safety of my children were significantly compromised. The loud popping noise startled us, and the fact that the rear seat lifted and detached posed a serious risk to the passengers in the back seat. Additionally, the gas leak created a fire and explosion hazard, putting all occupants of the vehicle and other drivers on the road at serious risk. This incident potentially violates the Fuel System Integrity (49 CFR 571.301) regulation, which ensures that a vehicle's fuel system is designed to prevent leaks and fire hazards. Moreover, the unexpected movement and detachment of the rear seat could be a breach of Occupant Protection (49 CFR 571.207 and 571.208), which govern the safety of seating systems and occupant crash protection. The issue has been confirmed by the service center at College Park Hyundai, where the vehicle is currently being inspected and evaluated. The vehicle is being inspected by the manufacturer’s authorized service center at College Park Hyundai. It has not yet been inspected by police or insurance representatives at this time. The check engine light came on immediately after the loud popping noise and the detachment of the rear seat cushion. Additionally, the gas gauge suddenly dropped to empty after the incident, even though the tank was not empty prior to the malfunction.

I was driving back from Atlanta, GA to Pensacola, FL when we noticed our fuel level dropping significantly. We stopped in West Point, GA to see what was going on. We turned the car off and back on after 3 minutes and car made a weird vibration. Then the fuel level was rising back to normal but my wife was in the backseat with our [XXX] and she noticed the seat was rising and creating a lot of heat. We pulled over again and noticed it wasn't going down. Luckily there was a mechanic at this gas station and he informed us that the fuel tank expanded and to NOT drive the vehicle. We we're driving alongside my parents so we got in their car and drove back to Pensacola to get a truck and tow attachment cause a tow truck would've costed us $2,500 to tow back to Pensacola. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

(August 29th) My girlfriend and I were driving in my 2020 Sonata, when the check engine light turned on and my gas gauge dropped from being full to then only half way. About an hour later, driving back home we heard a loud pop as if something exploded. Next day, I took my car to the Autonation Hyundai dealership and after taking a look at my car they quoted me about $6,000 to get my fuel tank and charcoal canister replaced. Our safety was put at risk due to the fact that had the damage been any worse, it could have caused the car to possibly explode or give out while driving on the highway, and in turn would put many more lives at risk.

Gas tank is swelling causing the rear seats to pop up

Gas tank replaced three times and failed each installation (excess pressure)leaked gas with riders in car. I was a LYFT driver .YES car can be seen at MAUI HYUNDAI SERVICE DEPT 260 HANA Highway. Kahului, HI. 96732 Car needs another gas tank and Manager at Service Dept tells me there is only one gas tank available, the type we installed. FARMERS INSURANCE HAS SEEN PHOTOS OF THE BAD GAS TANK. Service department was not aware of this gas tank issue...told me you must have run over some debris (not true) HYUNDAI has received my complaint but not replied yet.Engine warning light came on went off came on Took car to dealer for service

Riding down the road June 30, 2024 and heard a loud boom coming from the back of my car. I pulled to the side of the road and walked around but saw no damage to outside of car. When I was approximately 30 miles from home my gas started dropping tremendously. Once arriving at home it was a rumble coming from rear of car after inspecting outside car and seeing no damage again, I looked in my back seat and the rear seat was lifted. If my kids or any other occupants would have been back there it could have possibly caused injuries. Upon my mechanic looking my car over they told me it was something to do with my fuel tank. My appointment is July 16, 2024 Hyundai of Dothan in Dothan al for farther diagnosis. My safety was in danger as explosion from the fuel tank could have cause serious damage and/or injury to car and self. Check engine light came on once the fuel consumption started dropping tremendously.

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

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.

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.

There is an issue with the 2020+ Hyuandai sonatas and Kia K5 models. The valves in my gas tank had failed. Causing pressure and gas vapors to be trapped inside the tank. The pressure in my tank has swollen my gas tank to the point where it’s bent the metal frame underneath my backseat, lifting my backseat off its base. My car is a literal tricking time bomb because the tank will eventually burst. There’s also a strong smell of gas coming from underneath the backseat. There’s been a new story on this issue already. Kia has acknowledged the issue and did recalls. Hyundai has not. Many owners of the Sonata are having this same exact issue according to Reddit posts. I took my vehicle to the dealer, got it diagnosed, was quoted $2900+. I was told it was an extreme safety hazard due to the pressure in the tank and the gas leak. The tank has swollen so much that it’s pressing against the exhaust. I’m out of warranty and they expect me to pay out of pocket. I have no where near $3000. I use my car for work and have no choice but to drive it. Please help.

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...