Hyundai · Known Issues
2021 Hyundai Sonata Problems: 5 Known Issues
2021 model year · 940+ owner reports · Updated September 2026
2021 · All trims · All engines
Choose the year and equipment for your written issues and visual request.
2021 model year · 940+ owner reports · Updated September 2026
2021 · All trims · All engines
Choose the year and equipment for your written issues and visual request.
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According to Au7o's analysis of 940+ owner reports, the 2021 Hyundai Sonata has 5 documented known issues, with 2 rated critical. The most serious are Eight-Speed Wet DCT Electric Oil Pump Failure Causing Total Loss of Drive (DN8) ($0-$5,500 repair) and No Engine Immobilizer on Turn-Key Trims Enabling USB-Cable Theft ($0-$900 repair). The most commonly reported issue is Infotainment System Freezing/Issues with 520 owner reports. Across all issues with published estimates, repair costs range from $100 to $5,500. DIY maintenance guides at au7o.io.
FUEL SYSTEM, GASOLINE:DELIVERY:HOSES, LINES/PIPING, AND FITTINGS
Hyundai Motor America (Hyundai) is recalling certain 2021-2022 Santa Fe and Sonata vehicles equipped with 2.5L turbocharged engines. Fuel may leak at the pipe connection between the high-pressure fuel pump and fuel rail.
VISIBILITY:WINDSHIELD
Hyundai Motor America (Hyundai) is recalling certain 2020-2021 Santa Fe, 2021 Sonata, and Elantra vehicles. During manufacturing, the windshield may not have been properly bonded to the vehicle, allowing it to detach in a crash.
POWER TRAIN:AUTOMATIC TRANSMISSION
Hyundai Motor Company (Hyundai) is recalling certain 2021-2022 Santa Fe, Sonata, Veloster N, 2022 Santa Cruz, Elantra N, and Kona N vehicles. The vehicle's "fail-safe" limited-mobility drive mode may be impaired, when prompted by a transmission oil pump malfunction, which can result in a complete loss of drive power.
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According to Au7o's analysis of 940+ owner reports, the 2021 Hyundai Sonata has 5 documented issues. The most frequently reported are: Eight-Speed Wet DCT Electric Oil Pump Failure Causing Total Loss of Drive (DN8), No Engine Immobilizer on Turn-Key Trims Enabling USB-Cable Theft, Fuel Injector Failure Causing Misfire, Rough Running, and Check Engine Light. Of these, 2 are rated critical and should be addressed promptly.
The 2021 Hyundai Sonata has 5 known issues documented across 940+ owner reports. 2 issues are rated critical: Eight-Speed Wet DCT Electric Oil Pump Failure Causing Total Loss of Drive (DN8) and No Engine Immobilizer on Turn-Key Trims Enabling USB-Cable Theft. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.
Repair costs for known Hyundai Sonata issues range from $0 to $5,500, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Eight-Speed Wet DCT Electric Oil Pump Failure Causing Total Loss of Drive (DN8), typically costs $0-$5,500 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
On the DN8 Sonata the electric oil pump inside the eight-speed wet dual-clutch transmission can fail abruptly, collapsing internal oil pressure. The transmission's limited-mobility fail-safe mode is impaired when the failure is triggered this way, so instead of degrading to a red… Repairs typically run $0-$5,500. Severity: high.
Sonatas built without a push-button start system were sold in the US without an engine immobilizer, meaning the starter and ignition can be operated with a stripped steering column and a USB plug rather than a coded key. The technique was spread on TikTok from 2021 by the 'Kia Bo… Repairs typically run $0-$900. Severity: high.
Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.
FUEL SYSTEM, GASOLINE
Hyundai Motor America (Hyundai) is recalling certain 2020-2023 Sonata vehicles. A damaged check valve can allow air to enter the fuel tank, causing it to expand and contact hot exhaust components, melting the tank.
ELECTRICAL SYSTEM:SOFTWARE
Hyundai Motor America (Hyundai) is recalling certain 2020 Nexo and Sonata vehicles. The Remote Smart Parking Assist (RSPA) software may fail to prevent vehicle movement upon detection of an RSPA system malfunction.
+ 3 more recalls. Check all on NHTSA.gov
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Hyundai TSB 25-FL-001H covers specified production ranges of model-year 2021-2023 Sonata vehicles equipped with the 2.5-liter GDI Theta III non-turbo engine. Some affected vehicles may store one or more misfire DTCs due to GDI injectors leaking internally; the bulletin says inter… Severity: medium.
The infotainment system can freeze, become unresponsive, or experience connectivity issues. Bluetooth pairing problems, navigation crashes, and touchscreen lag are common complaints. Repairs typically run $0-$800. Severity: low.
Some Sonata owners experience unexplained battery drain, resulting in a dead battery after sitting for several days. Various electronic modules may not go to sleep properly. The smart key system can also contribute to drain. Repairs typically run $100-$500. Severity: low.