2021 Hyundai Sonata Owner Complaints

DESCRIPTION OF SAFETY DEFECT & IMMEDIATE HAZARD:My 2021 Hyundai Sonata SEL is currently exhibiting the most severe, catastrophic symptoms of the fuel tank expansion defect covered under NHTSA Campaign 25V796000. The fuel tank has expanded so drastically that it physically warped the structural interior of the cabin, violently popping the rear passenger seat completely out of its assembly while the vehicle was in motion. Furthermore, there is a constant, heavy, raw gasoline odor inside and around the vehicle. The vehicle is a documented, active fire, explosion, and vapor inhalation hazard. It is currently physically located at Sterling Hyundai in Lafayette, LA.DESCRIPTION OF MANUFACTURER NON-COMPLIANCE & REFUSAL TO REMEDY:Hyundai Motor America and Sterling Hyundai are in direct violation of their legal obligation to provide a safe, accessible remedy or interim safety accommodations under federal recall guidelines. An Executive Case Manager from Hyundai Corporate has officially refused to provide a direct-billed rental vehicle or a dealer loaner.Initially, a third-party rental vehicle was provided. However, that vehicle was compromised in an accident and wrecked through absolutely no fault of my own. Despite my lack of fault, Hyundai Corporate and the dealership are now explicitly using that accident to refuse any further direct-billed rental accommodations or dealer loaners.Instead, they are demanding that I pay out-of-pocket for a rental vehicle at a rate of $60/day for a repair process expected to take multiple weeks, knowing I do not possess the upfront financial means to cover these costs. By imposing this insurmountable financial barrier due to an accident I did not cause, Hyundai has effectively stranded me. Because I must maintain my livelihood and have no other means of transportation, Hyundai’s bad-faith refusal to direct-bill an accommodation is actively forcing me to retrieve and operate a verified, explosive fire hazard.REMEDY SOUGHT:I request that the NH

NHTSA ID

11766388

Incident

Sep 23, 2026

The contact owns a 2021 Hyundai Sonata. The contact received notification of NHTSA Campaign: 25V796000 (Fuel System, Gasoline); however, parts were on back order. The contact stated that while driving at an undisclosed speed, the vehicle jerked with an abnormal gasoline odor inside the vehicle. An unknown warning light was temporarily illuminated. Upon further inspection, the contact became aware that the fuel level had dropped. The vehicle was taken to a local dealer where it was diagnosed with an expanded fuel tank. The contact stated that the O2 sensor, spark plugs, and ignition coils were replaced by a local independent mechanic; however, the failures persisted. The contact had headaches while driving the vehicle. Medical attention was not needed. The manufacturer was made aware of the failure. The failure mileage was approximately 100,000.

NHTSA ID

11765048

Incident

Sep 15, 2025

Mileage

100,000 mi

Transmission replaced twice and all of them continue to fail. Several Hyundai service centers are unable to determine the cause and are only able to update/relearn and replace whenever they are able to replicate the issue. The issue is that at a cold start, the car makes a popping sound, jerks and shakes. The car hesitates to accelerate. You can hear the noise of acceleration but RPM does not go past 3 and MPH doesn't go past 30mph. I'm unable to upload docs because of the upload limit. If there's another way to send docs, please let me know

NHTSA ID

11764277

Incident

Jan 26, 2023

Massive loss of coolant in closed loop cooling system Heat soak. Fail safe mode

NHTSA ID

11759867

Incident

Apr 15, 2026

The contact owns a 2021 Hyundai Sonata. The contact received notification of NHTSA Campaign Number: 25V796000 (Fuel System, Gasoline); however, the part to do the recall repair was not yet available. The contact stated that while driving at an undisclosed speed, the vehicle independently accelerated and decelerated while the accelerator pedal was depressed. The check engine warning light was illuminated. The vehicle was towed to a local dealer where it was diagnosed with an expanded frame due to an expanded fuel tank. The vehicle was deemed too expensive to repair per the local dealer and was towed for a buy-back. The manufacturer was made aware of the failure, but no assistance was provided. The failure mileage was approximately 55,000.

NHTSA ID

11758588

Incident

Dec 15, 2025

Mileage

55,000 mi

I took my vehicle in for the safety recall due to an expanding fuel tank on 08/03/2026. I received my vehicle back on 8/12/2026. Hyundai performed an improper repair on the vehicle that will not correct the fuel tank expansion. They replaced the same check valve that was replaced last time I brought the vehicle in for recall on 11/20/2024 repair order # 107221 at Jones Hyundai of Belair. This valve did not and will not correct the fuel tank expansion issue. The expansion issue is caused by fuel getting past the check valve and entering the purge control system. The correct repair is to replace the fuel tank and the purge control system, as the check valve has already allowed fuel to bypass it and enter the system causing the expansion issue. . Replacing the valve that failed & allowed fuel into the system & caused the tank to expand will not correct the issue caused by the failed valve. My fuel tank has not decompressed. I still have the same problem I brought the vehicle in for because the repair Hyundai advised NHTSA on was NOT performed.

NHTSA ID

11757244

Incident

Aug 12, 2026

Gas tank expansion and pcv melted. Car smells like gas when I was driving earlier, and my garage was flooded with the fumes of gasoline.

NHTSA ID

11755570

Incident

Aug 7, 2026

The Left blinker switch keeps going in and out, working about 50% of the time. Both the light and the blinker sound do not turn on. When getting it checked out at an auto repair shop, the maintenance tech said this was more and more common for 2021 sonatas and it was not due to anything I did. It was a multifunction switch problem.

NHTSA ID

11755451

Incident

Aug 1, 2026

The contact owns a 2021 Hyundai Sonata. The contact stated that while driving at an undisclosed speed, the fuel gauge indicated that the tank was half full. The contact stated that the gauge erroneously indicated that the tank was empty, and the check engine warning light was illuminated. The vehicle was driven to the gas station, and while attempting to refuel the vehicle, the fuel did not go into the tank. The vehicle was towed to the residence. The vehicle was later towed to the dealer, where it was diagnosed with a failed fuel system and a failed fuel tank. The contact was informed that the fuel system and fuel tank needed to be replaced. The vehicle was not repaired. The contact was informed that the failure was associated with the unrepaired recall. The contact was informed that the vehicle was a fire risk. In addition, the contact was informed that there was a hole in the fuel tank that caused the fuel to leak out of the fuel tank. The contact was informed that the parts were ordered to repair the vehicle. The contact received notification of NHTSA Campaign Number: 25V796000 (Fuel System, Gasoline). The manufacturer was not made aware of the failure. The failure mileage was approximately 50,200.

NHTSA ID

11754791

Incident

Jul 28, 2026

Mileage

50,200 mi

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

NHTSA ID

11754136

Incident

Jul 31, 2026

1. Component Failed: Panoramic Sunroof Glass Assembly (Structure / Visibility / Glass). Details: While traveling at highway speed on the freeway, the panoramic sunroof glass spontaneously exploded outward without warning or impact from any foreign object. Inspection: I have not had the vehicle repaired yet so it is currently available. I also took a picture of it. 2. Safety Risk: The sudden, loud explosion (sounding like a gunshot) at freeway speeds caused immediate driver distraction and severe disorientation. Shattered tempered glass was mostly restricted from the cabin by the curtain barrier but some rained down into the passenger cabin. Most blew backward onto the highway, posing a major hazard to occupants as well as trailing motorists. Furthermore, this is a recurring defect in our household: my wife experienced an identical spontaneous sunroof explosion on her 2024 Hyundai Palisade, demonstrating a pattern of hazardous glass failures across multiple late-model Hyundai vehicles. 3. Reproduced or confirmed: I have not had it inspected by anyone. I am awaiting quotes for repairs. I have taken a picture of the vehicle that has not been driven since the incident. 4. Inspection: No one else has inspected it. I have a picture and can take more as needed. Hoping to not have to drive it until I take it to a shop for repairs. It has been reported to a dealership, but they did not seem too concerned or interested in helping. They insisted that they would not give a repair quote until I drove it the 20 miles for them to inspect. 5. Any Warning: No warning. There were no warning lights, abnormal noises, visible cracks, or previous symptoms prior to the sudden explosion. The failure occurred completely spontaneously under normal highway driving conditions.

NHTSA ID

11753241

Incident

Jul 22, 2026

Engine revving at a complete stop. Surging engine while braking. I was forced to put into neutral when stopping. I had check engine prior that read P049D85. It went away. The Hyundai dealer said to be the EGR valve. Nick Hayes at D'Arcy Hyundai and Hyundai Motor America (HMA) agreeing to a 75% goodwill split of cost to repair.

NHTSA ID

11753130

Incident

Jul 25, 2026

The contact owns a 2021 Hyundai Sonata. The contact received notification of NHTSA Campaign Number: 25V796000 (FUEL SYSTEM, GASOLINE); however, the part to do the recall repair was unavailable. The local dealer was contacted, and it was confirmed that the part was not yet available. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue. The vehicle was taken to the local dealer, and the contact was informed that the fuel tank was swollen and needed to be replaced. The vehicle was not yet repaired. The failure mileage was 80,484.

NHTSA ID

11753027

Incident

Jul 27, 2026

Mileage

80,484 mi

The panoramic sunroof spontaneously exploded while driving without any external impact

NHTSA ID

11752333

Incident

Jul 18, 2026

The contact owns a 2021 Hyundai Sonata. The contact stated that while driving 10 MPH and attempting to make a right turn, the brakes independently activated. Neither the dealer nor an independent mechanic was contacted. The check engine warning light was illuminated. The contact stated that the failure had occurred on several occasions. The vehicle was taken to the dealer and an independent mechanic to be diagnosed. The manufacturer was not notified of the failure. The approximate failure mileage was 42,000.

NHTSA ID

11747445

Incident

Jan 15, 2026

Mileage

42,000 mi

At approximately 130,000 miles, vehicle developed and internal coolant leak caused by a failed Exhaust Heat Recovery System (EHRS) in the center muffler assembly, matching TSB 23-EM-009H - a known manufacturing defect documented by Hyundai. Coolant has been slowly leaking internally into the exhaust system. The authorized Hyundai dealership initially failed to diagnose the internal leak and told me there was no leak and wanted to send me home. After pushing back, the internal leak was confirmed. If not caught, this defect could result in engine overheating or complete engine failure without warning. Hyundai Motor America has denied goodwill coverage despite this being a documented manufacturing defect.

NHTSA ID

11746137

Incident

Jun 22, 2026

The vehicle has experienced repeated transmission and Electronic Oil Pump (EOP) failures resulting in loss of propulsion, loss of acceleration, and transmission-related malfunctions. The vehicle currently has approximately 69,000 miles. On September 3, 2022, the vehicle lost propulsion while traveling approximately 31 MPH in traffic and would not respond normally to accelerator input. This created a dangerous situation and increased the risk of a collision. On the same date, while backing out of a parking space, the vehicle displayed a "Shifter System Malfunction" warning message and unexpectedly stopped while in reverse. The vehicle had to be powered off before it would operate again. Following these incidents, the vehicle was towed to a Hyundai dealership and the transmission was replaced in September 2022. Despite the transmission replacement, the vehicle continued experiencing issues involving the same system. The Electronic Oil Pump (EOP) was replaced in 2023 and again in 2024 due to recurring transmission-related concerns and diagnostic codes. In 2026, the check engine light returned and the vehicle was again diagnosed with a transmission-related failure. The dealership determined that the transmission requires replacement for a second time despite the previous transmission replacement and two separate EOP replacements. Internally, Hyundai has since revised its repair guidance for this condition, suggesting that prior repair procedures may not have fully addressed the underlying defect. The repeated failures of the transmission and EOP system despite multiple repairs suggest an underlying defect that has not been corrected. These failures create a significant safety risk because the vehicle can unexpectedly lose propulsion or fail to accelerate while operating in traffic. The vehicle is available for inspection upon request.

NHTSA ID

11741226

Incident

Sep 3, 2022

The car will idle high around 1200 rpms. The car will most of the times fix the issue when you turn the car off and back on but it will start again after driving. This is a known issue with the car. I have had the egr valve replaced since it will pop up the codes P240F and P049 for egr slow response and control position exceeded learning limit but the problem came back within two days. I did find a forum that deals with the joint connector repair but this needs to be a recall as I have come across many people who have this problem and paying out of pocket to fix it.

NHTSA ID

11741201

Incident

Mar 23, 2026

I took my car to dealer to repair recall. Dealer told me if it failed they would keep car and report stolen if I tried to take it. They failed it. I didn't trust them based on their report it stolen statement. I had the police get my car back. I took it to another dealer where it passed recall easily. I believe they wanted my car for a customer, and tried to get away with this ruse.

NHTSA ID

11739443

Incident

Mar 24, 2026

The contact owns a 2021 Hyundai Sonata. The contact stated while driving at an undisclosed speed, the engine shuddered and the engine stalled. In addition, the engine seized. No warning lights were illuminated. The contact stated that the vehicle was seized in the middle of the road. The contact stated that while attempting to start the vehicle, the vehicle started. The failure reoccurred. The vehicle was towed to the residence. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was made aware of the failure. The failure mileage was approximately 140,000.

NHTSA ID

11738864

Incident

May 18, 2026

Mileage

140,000 mi

The Exhaust Heat Recovery System (EHRS) has failed for the second time on this vehicle. The first failure occurred at approximately 35,000 miles and was repaired under Hyundai Technical Service Bulletin 23-EM-009H, which Hyundai issued to address this exact defect across 2020-2023 Sonata Hybrid models. The vehicle has now reached 71,000 miles and is experiencing the identical symptoms: coolant loss, overheating, and white exhaust smoke. The EHRS shares a coolant loop with the hybrid battery thermal management system. Coolant loss from this failure puts the hybrid battery and power electronics at risk of overheating, creating a potential fire and safety hazard. The recurring nature of this failure following an official TSB repair suggests the root cause has not been adequately addressed by Hyundai's current repair protocol.

NHTSA ID

11730992

Incident

Aug 10, 2024

• I experienced trouble with my splash guard being damaged from hanging and scraping the ground about a month after purchasing the vehicle. Also, my hood paint started chipping after a recent cold front experienced in my state earlier this year. Yes it is available for inspection upon request. Regarding the splash guard, not applicable. • It’s was very inconvenient to drive with a portion of my car scraping the ground. I had to be more mindful of my driving in the higher speed limit areas incase the splash guard detached. I had it re-attached multiple times. Regarding the chipped paint, not applicable. • It it counts, for my splash guard, during a servicing, I asked Hyundai to re-attach it. For the chipped paint, no. • The splash guard has during a past servicing. The chipped paint is more recent so it hasn’t • No. Splash guard, a month after purchasing vehicle. The chipped paint, earlier this year, January-February 2026.

NHTSA ID

11730039

Incident

Jan 30, 2026

I was notified of a recall on my from vehicle by Hyundai via email some time in March of 2026. The message said mentioned my vehicle may have a defective/worn purge control check valve that would cause the fuel tank to deform. Potentially leading to a release of fuel over time, which then could ignite. NHTSA Recall #25V796000 My car showed now signs of problems, but I brought it into a Hyundai dealership on March 13th where they confirmed my vehicle had the issue. They said the situation required I not drive my vehicle and gave me a rental in the meantime. I assumed it would be a simple swap of the fuel tank and everything would be fine. I was offered a buyback from my Hyundai claims manager over the situation, but I figured since its a simple fix, I'd keep my car and have it fixed. Two weeks went by with no update from the dealership, so I walked in for answers. Turns out, the subframe of my car has been damaged by the expanding fuel tank and they are still waiting for updates from Hyundai on how to proceed as they themselves don't know how to fix my vehicle. My Hyundai claims manager did not mention this when we talked over the phone and he offered a buyback. None of their recall notices mention structural damage anywhere or even as a possibility. I asked the dealership again on April 1, 2026, and they are still waiting on guidance on how to proceed. Neither does my Hyundai claims manager handling this situation on their end.

NHTSA ID

11729119

Incident

Mar 13, 2026

The internal core of the Exhaust Heat Recovery System (EHRS), part of the center muffler/front pipe assembly (#28600-L5210), suffered a catastrophic failure. This allowed approximately 9 gallons of engine coolant to leak directly into the hot exhaust stream. Safety Risk: This failure creates a severe visibility hazard. During acceleration from stop lights and stop signs, the vehicle emits massive, thick clouds of white glycol smoke. The smoke is so dense that it completely obscures the driver's view of trailing vehicles and prevents following drivers from seeing the roadway or my vehicle's brake lights, creating a high risk of rear-end collisions. Additionally, the rapid loss of coolant caused the engine to overheat and lose power while in motion, nearly causing a stall in active traffic. Confirmation: The failure was confirmed by the service department at Washington Hyundai (Invoice #174281). This is the second failure of this specific component (previously failed in Jan 2025). The manufacturer issued TSB 23-EM-009H for this defect, acknowledging it affects 2020-2023 Sonata Hybrids, but no safety recall has been issued. Symptoms: The issue was preceded by a "sweet" burning smell and a sudden "Engine Overheating" warning on the dashboard. The failed component has been replaced by the dealer, but the manufacturer refused to replace the coolant-poisoned Oxygen (O2) sensors, leaving the vehicle in a technically compromised state. The failed unit is likely held by the dealer for warranty parts return.

NHTSA ID

11727380

Incident

Feb 19, 2026

The contact owns a 2021 Hyundai Sonata. The contact received notification of NHTSA Campaign Number: 25V796000 (Fuel System, Gasoline); and the vehicle was taken to the dealer for the recall repair; however, the dealer informed the contact that the vehicle was unrepairable, and there was no further information provided. The manufacturer was made aware of the issue, and a case was filed. The manufacturer informed the contact that the field engineers had reviewed the vehicle and advised that a buyback was the best option. Additionally, the manufacturer offered an 8 percent discount on the purchase of a new vehicle. The contact declined the offer because the vehicle had not experienced a failure, and the vehicle would be paid off after two additional payments.

NHTSA ID

11725496

Incident

Mar 19, 2026