2021 Hyundai Sonata Common Problems & Defect Telemetry
Authoritative defect intelligence synthesized from 128 verified NHTSA owner complaints, 4 federal safety recalls, and interquartile failure mileage telemetry.
The 2021 Hyundai Sonata receives a 4.2/10 MazicBay Reliability Index based on 128 verified NHTSA federal complaints and 4 safety recalls. The primary reported failure mode is Engine Stalling, Oil Consumption & Cooling Defect Reports with a median failure point at 55,000 miles (IQR: 33,500 – 64,425 mi). Out-of-warranty repairs benchmark at $950 – $3,200 .
28.4 complaints / 10k sold
Verified US federal records
Crash, fire & stall audit
4 Active / Free Remedies
Top Reported Problem Clusters (7)
Engine Stalling, Oil Consumption & Cooling Defect Reports
- Engine sudden stall / hesitation while driving
- Abnormal oil burning / consumption
- Check Engine Light (MIL) flashing
- Engine overheating / coolant loss
“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 ...”
“Going down the road driving the car lost power and went in limp mode with no warnings on the dash at all!”
“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) ...”
Transmission Hesitation, Hard Shifting & Slipping Reports
- Hard gear shifts / delayed engagement into Drive/Reverse
- Transmission shudder / jerking under acceleration
- Transmission slipping between gears
“Going down the road driving the car lost power and went in limp mode with no warnings on the dash at all!”
“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 p...”
“Vehicle suddenly lost heat in 30 degree weather. No warnings, check engine light, or temperature gauge indicators came on. Lucky made it to a parts store and found out I was extremely low on coolant. Bought coolant and put it in. Made it back to the house and was immediately l...”
Electrical Parasitic Drain, Infotainment & Harness Reports
- Unexplained battery drain after sitting overnight
- Infotainment display / instrument cluster blackouts
- Accessory malfunction / alternator fault warnings
“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 t...”
“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 P04...”
“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-...”
Fuel Pump Pressure Loss & Fuel Delivery Defect Reports
- Sudden loss of propulsion power at highway speeds
- Extended engine cranking / failure to restart
- Fuel odor near fuel tank / engine bay
“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 repla...”
“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.”
“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 ...”
Service Brakes, ABS Actuator & Master Cylinder Reports
- Spongy or hard brake pedal travel
- ABS / Brake warning light illuminated
- Extended stopping distance / pedal vibration
“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 conta...”
“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 ...”
“Will be driving the car and suddenly hear a beep. Then the dashboard will flash with the ABS light engine light tire pressure light check Blindspot sensors, forward collision sensors. once all the lights appear on the dashboard, I can no longer accelerate. i’ve cleaned the thr...”
Electric Power Steering Assist & Suspension Noise Reports
- Sudden loss of electric power steering assist
- Steering wheel pull or highway wander
- Clunking / knocking noise over bumps
“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 no...”
“I took my car to the dealer on ... with concerns about the strong gas smell that I have been smelling. The Hyundai dealership kept my car for 3 days and stated they could not smell the gas after driving the vehicle themselves. They did repair a cracked cylinder head however th...”
“Engine makes rattling and knocking noises. Transmission hesitates and jerks Suspension front struts and rear shocks are bad. Possible the isolators. Having horrible back pain when riding in car. Starter intermittently doesn't work Lane keep assistance goes over small bump in r...”
Airbag Occupant Detection & Inflator Defect Reports
- SRS Airbag warning lamp illuminated
- Passenger occupant classification sensor failure
- Seat belt retractor lockup
“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 no...”
“The contact owns a 2021 Hyundai Sonata. The contact stated that while driving at an undisclosed speed, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. The vehicle was driven to the shoulder of the road. The contact stated that the fu...”
“P0471 error comes up off and on, this is recall related but the dealership refuses to address it. The seatbelt has to be clicked 2x in order to stick. Happens with driver side.”
Official NHTSA Safety Recalls (4)
FUEL SYSTEM, GASOLINE:DELIVERY:HOSES, LINES/PIPING, AND FITTINGS
Summary: 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
Summary: 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
Summary: 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.
FUEL SYSTEM, GASOLINE
Summary: 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.
Pre-Purchase Inspection Checklist for 2021 Hyundai Sonata
Before purchasing a used 2021 Hyundai Sonata, perform the following targeted inspections based on reported federal defect patterns:
Scan the OBD-II port under the dash for pending freeze-frame codes (e.g. P0300 misfires, P0087 fuel rail pressure, P0420 catalytic efficiency).
Test vehicle at low-speed stop-and-go and highway merges. Check for delayed reverse engagement or gear shift shudder between 2nd and 3rd gears.
Verify that all 4 NHTSA safety recall campaigns have been performed by an authorized dealership using the VIN.
Ensure the instrument cluster, center screen, and auxiliary charging ports operate with stable 12.0V–14.4V alternator voltage.
Defect & Reliability Q&A: 2021 Hyundai Sonata
Is the 2021 Hyundai Sonata a reliable used car?
The 2021 Hyundai Sonata earns a 4.2/10 MazicBay Reliability Index based on 128 federal owner reports. Vehicles maintained under factory service schedules exhibit strong longevity past 150,000 miles.
What is the most frequent defect reported on the 2021 Hyundai Sonata?
The leading complaint category is Engine Stalling, Oil Consumption & Cooling Defect Reports, with a median failure point around 55,000 miles (IQR: 33,500 – 64,425 mi).
Are there free recall repairs available for the 2021 Hyundai Sonata?
Yes, the NHTSA records 4 safety recall campaign(s) for this model year. All safety recalls are performed 100% free of charge by authorized franchise dealerships regardless of vehicle warranty status.