2021 Hyundai Sonata
Vehicle Specs & Maintenance Data
The 2021 Hyundai Sonata maintenance specs on this page cover the key fluids, torque values, and wear items you need for routine service. Use these numbers as a quick reference when performing oil changes, tire rotations, brake jobs, and other scheduled maintenance on your Hyundai Sonata.
For oil changes, the 2021 Hyundai Sonata takes 5W-30 Full Synthetic motor oil with a capacity of 4.2 quarts. Brake fluid type is DOT 3, the recommended coolant is Phosphate-based Green/Blue, and transmission fluid is SP-IV-M (ATF). Always use the manufacturer-recommended fluids to maintain warranty coverage and engine longevity.
When mounting wheels on the Hyundai Sonata, torque the lug nuts to 79-94 ft-lbs using a calibrated torque wrench. Over- or under-torquing can lead to warped brake rotors or loose wheels. Re-torque after 50 to 100 miles on newly installed wheels.
Owners of the 2021 Hyundai Sonata have reported 5 common issues including "Fuel Tank Expansion and Fire Risk", "DCT Transmission Oil Pump Failure" and "High-Pressure Fuel Pipe Leak (2.5T)". Scroll down to the Diagnostics tab for detailed descriptions, solutions, and estimated repair costs.
There are 4 NHTSA safety recalls on file for the 2021 Hyundai Sonata. Check the Recalls tab below for full details.
Specifications on this page are compiled from multiple publicly available sources including manufacturer documentation, NHTSA data, and automotive databases. Always cross-reference with your owner's manual or official factory documentation before purchasing parts or performing any service.
The 2021 Hyundai Sonata uses 5W-30 Full Synthetic motor oil (4.2 qt capacity), requires lug nuts torqued to 79-94 ft-lbs, takes DOT 3 brake fluid.
Manufacturer-recommended maintenance schedule for the 2021 Hyundai Sonata. Always verify intervals against your owner's manual.
Enter a diagnostic trouble code to see causes, symptoms, and fixes for the 2021 Hyundai Sonata.
Common problems reported by 2021 Hyundai Sonata owners, with recommended fixes and estimated repair costs.
Fuel Tank Expansion and Fire Risk
A damaged check valve can allow air to enter the fuel tank, causing it to expand and contact hot exhaust components, melting the tank. This creates a serious fire risk. Owners may notice a fuel smell, fuel tank deformation, or a check engine light related to the evaporative emissions system.
Hyundai issued a recall covering 2020-2023 Sonata vehicles. Dealers will replace the check valve and inspect the fuel tank, replacing it if necessary, free of charge. Owner notification letters were mailed January 2026.
Est. Cost: Covered under recallDCT Transmission Oil Pump Failure
Vehicles with the 8-speed dual-clutch transmission may experience a transmission oil pump malfunction that impairs the fail-safe limited-mobility drive mode, potentially resulting in a complete loss of drive power while driving. Symptoms include sudden loss of acceleration, warning lights, and the vehicle coasting to a stop.
Hyundai issued recall 22V-794 for 2021-2022 Sonata DCT models. Dealers will inspect and replace the transmission as necessary and update the TCU software free of charge.
Est. Cost: Covered under recallHigh-Pressure Fuel Pipe Leak (2.5T)
On Sonata models equipped with the 2.5L turbocharged engine, fuel may leak at the pipe connection between the high-pressure fuel pump and fuel rail. A fuel leak near hot engine components significantly increases the risk of an engine compartment fire.
Hyundai issued a recall for 2021-2022 Sonata 2.5T models. Dealers will inspect and tighten or replace the fuel pipe as necessary, free of charge.
Est. Cost: Covered under recallEngine Stalling and Hesitation
Some owners report the engine hesitating or stalling during acceleration, particularly when pulling away from a stop or merging onto highways. The issue is often linked to transmission software calibration and throttle mapping. Cold weather may exacerbate the symptoms.
Hyundai has released ECU and TCU software updates to reduce hesitation when accelerating from a stop and improve shift quality. Dealers will apply the latest calibration update. Multiple TSBs address this concern.
Est. Cost: $0 under warranty; $100 - $200 for software update out of warrantyExhaust System Rattle and Catalytic Converter Issues
Owners report rattling noises from the exhaust system, particularly from the catalytic converter heat shield. Some vehicles also experience premature catalytic converter failure, triggering check engine lights with catalyst efficiency codes (P0420). The exhaust heat recovery system can also develop leaks.
Have the dealer inspect the exhaust system for loose heat shields and tighten or replace them. For catalytic converter issues, the repair is covered under the federal emissions warranty (8 years/80,000 miles). Hyundai has TSBs addressing exhaust heat recovery system concerns.
Est. Cost: $100 - $300 for heat shield; $0 under emissions warranty for converter4 NHTSA safety recalls for the 2021 Hyundai Sonata. Check your VIN at NHTSA.gov
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.
A melted fuel tank can leak, increasing the risk of a fire.
Dealers will inspect and replace the check valve. The fuel tank assembly will be inspected for damage and replaced if necessary. Additionally, dealers will inspect and update the engine control unit software. All repairs will be performed as necessary, free of charge. Interim notification letters, notifying owners of the safety risk, were mailed beginning January 15, 2026. Additional letters will be sent once the final remedy is available. Owners may contact Hyundai customer service at 1-855-371-9460. Hyundai's number for this recall is 286. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov on November 19, 2025.
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.
Loss of drive power increases the risk of a crash.
Dealers will inspect and replace the transmission, as necessary. Dealers will also update the transmission control unit software. All repairs will be performed free of charge. Owner notification letters were mailed January 10, 2023. Owners may contact Hyundai customer service at 1-855-371-9460. Hyundai's number for this recall is 236.
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.
A windshield that detaches from a vehicle during a crash can increase the risk of injury.
Dealers will remove and reinstall the front windshield panel, free of charge. Owner notification letters were mailed June 20, 2022. Owners may contact Hyundai customer service at 1-855-371-9460. Hyundai's number for this recall is 216.
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.
A fuel leak increases the risk of a fire.
Dealers will inspect and tighten, or replace the fuel pipe as necessary, free of charge. Owner notification letters were mailed on September 3, 2021. Owners may contact Hyundai customer service at 1-855-371-9460. Hyundai's number for this recall is 207.