2021 Hyundai Sonata problems

Filed Oct 23, 2026 · Electrical · AZ

The left turn signal works intermittently. It has now stopped working about 90% of the time. The multi-function switch was replaced 3 times and I am still having the issue. The signal won't work on the exterior and it won't light up on the interior dash either. This is creating an unsafe driving environment which increases crash rates. Multiple vehicle owner with the same make/model/year are experiencing this issue, which I have found during research.

Filed Sep 28, 2026 · Transmission · UT

My 2021 Hyundai Sonata N Line suffered a catastrophic, sudden total loss of drive power while operating at speed on a public roadway, creating an immediate crash hazard. The vehicle lost forward propulsion and the gear selector flashed a blinking 'R' when reverse was attempted. The vehicle was towed to an authorized dealer, [XXX] Hyundai Southtowne, where their factory GDS tool pulled transmission code P283601 (Shift Fork 'B' Position Circuit). This matches the exact critical safety failure path targeted by Federal Safety Recall 236 (the federal safety agency Campaign 22V‑746) for the 8-speed wet-DCT high-pressure electric oil pump circuit failure. The vehicle previously received the 2022 software patch, but the underlying physical hardware has now actively degraded. The dealership is attempting to deny the federal safety recall remedy based on the vehicle's high mileage. An active corporate consumer affairs investigation has been opened under Case #XXX. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Sep 23, 2026 · Fuel system · LA

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 the federal safety agency 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

Filed Sep 17, 2026 · Fuel system · 100,000 miles · LA · 1 injury

The contact owns a 2021 Hyundai Sonata. The contact received notification of the federal safety agency 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.

Filed Sep 15, 2026 · Transmission · TX

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

Filed Aug 26, 2026 · Driver assistance, Transmission · FL

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

Filed Aug 21, 2026 · Fuel system · 55,000 miles · IL

The contact owns a 2021 Hyundai Sonata. The contact received notification of the federal safety agency 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.

Filed Aug 16, 2026 · Fuel system · MD

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 the federal safety agency on was NOT performed.

Filed Aug 7, 2026 · Fuel system · TX

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.

Filed Aug 7, 2026 · Electrical · OH

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.