Owners have filed 71 complaints
about the 2021 Hyundai Sonata Hybrid with NHTSA between 2021 and 2026.
The largest single group is the electrical system.
Across this model's run it ranks 10 of 14 worst.
The letter says how bad. This says what kind — whether this year drew
an unusual number of complaints, unusually dangerous
ones, or failures that arrived unusually early.
The dashed ring is 50 — the national norm. Further out is worse.
Complaint volume — 43
Against the median year of the Hyundai Sonata Hybrid. 50 means typical for this
model; 100 means roughly double.
Severity — 44
8.5% of these complaints
involved a crash, fire, injury or death, against a national rate of
9.7%.
Early failure — not reported
Too few complaints recorded a mileage to measure this.
How 2021 compares with every other Hyundai Sonata Hybrid
The agency crash-tested this model year itself. These are its own
photographs and star ratings.
Frontal crash test
Side barrier crash test
Side pole crash test
Photographs taken by NHTSA during its own New Car Assessment Program crash
tests of this model year. Public domain.
Configuration
Overall
Front
Side
Rollover
2021 Hyundai Sonata Hybrid 4 DR FWD
9.7% risk
When owners complained
A spike years after the car went on sale usually means a part wearing
out on schedule across the whole fleet — the kind of pattern no single
owner can see from inside their own car.
Oct 2021peak 7Aug 2026
NHTSA investigations into the 2021 Hyundai Sonata Hybrid
An investigation is the step before a recall: the agency has seen enough
complaints to look into a pattern itself. An open one means it thinks
something may be wrong and nothing has been fixed yet.
DP22005Opened 27 Jan 2023Closed 7 Aug 2023ELECTRICAL SYSTEM:PROPULSION SYSTEM
Pedestrian alert sounds
NHTSA received a petition on or about July 18, 2022, requesting that Federal Motor Vehicle Safety Standard (FMVSS) 141 be applied to all electric and hybrid vehicles operating in the United States. The petition can be reviewed at NHTSA.gov under ODI Number 11486072. FMVSS 141 establishes performance requirements for pedestrian alert sounds for motor vehicles. The standard applies to hybrid and electric vehicles that have a gross vehicle weight rating of 4,536 KG or less or are defined as low-speed vehicles. The standard became fully applicable to all such vehicles manufactured on or after Marc...
Complaints that involved harm
Reports where the owner recorded a crash, a fire, an injury or a death.
Merrimac, MACrash2 injured
FORWARD COLLISION AVOIDANCE: WARNINGS
The forward collision warning, automatic emergency braking and adaptive cruise control failed as the first 2 activated when there were no oncoming collisions in front of me and the nearest cars around me were 1/4 of a mile away. The cruise control failed as it turned back on after the vehicle veered off the highway and into the rest stop. My safety and the safety of a lot of other people in the rest stop were put at risk because the system malfunction and tripped when no other cars were present that would have led to a collision. The vehicle led me off the highway into the rest stop where others could have been fatally hurt. I ended up with a shattered left foot that required a major reconstructive surgery to mend but the break will affect me the rest of my life, with more problems developing later on in life as well. No one inspected the vehicle or listened to what I had to say. No investigations were launched by insurance, the manufacturer or the police. If anything, insurance and the manufacturer seemed like they were in a hurry to dispose of the vehicle, urging me to release vehicle where it was sent to after the crash to one of insurance centers. The collision warning light came on and the vehicle responded by hard braking and veering to the right, then the cruise control turned back on and accelerated into the rest stop, first bouncing up the curb and onto the dirt, hitting a sign on the passenger side then bouncing off a tree on the driver side and finally T-boned a parked boat on a trailer head on. The vehicle was a total loss
NHTSA complaint #11508517 — an unverified report by a vehicle owner.
Merrimac, MACrash2 injured
FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL
The forward collision warning, automatic emergency braking and adaptive cruise control failed as the first 2 activated when there were no oncoming collisions in front of me and the nearest cars around me were 1/4 of a mile away. The cruise control failed as it turned back on after the vehicle veered off the highway and into the rest stop. My safety and the safety of a lot of other people in the rest stop were put at risk because the system malfunction and tripped when no other cars were present that would have led to a collision. The vehicle led me off the highway into the rest stop where others could have been fatally hurt. I ended up with a shattered left foot that required a major reconstructive surgery to mend but the break will affect me the rest of my life, with more problems developing later on in life as well. No one inspected the vehicle or listened to what I had to say. No investigations were launched by insurance, the manufacturer or the police. If anything, insurance and the manufacturer seemed like they were in a hurry to dispose of the vehicle, urging me to release vehicle where it was sent to after the crash to one of insurance centers. The collision warning light came on and the vehicle responded by hard braking and veering to the right, then the cruise control turned back on and accelerated into the rest stop, first bouncing up the curb and onto the dirt, hitting a sign on the passenger side then bouncing off a tree on the driver side and finally T-boned a parked boat on a trailer head on. The vehicle was a total loss
NHTSA complaint #11508517 — an unverified report by a vehicle owner.
The forward collision warning, automatic emergency braking and adaptive cruise control failed as the first 2 activated when there were no oncoming collisions in front of me and the nearest cars around me were 1/4 of a mile away. The cruise control failed as it turned back on after the vehicle veered off the highway and into the rest stop. My safety and the safety of a lot of other people in the rest stop were put at risk because the system malfunction and tripped when no other cars were present that would have led to a collision. The vehicle led me off the highway into the rest stop where others could have been fatally hurt. I ended up with a shattered left foot that required a major reconstructive surgery to mend but the break will affect me the rest of my life, with more problems developing later on in life as well. No one inspected the vehicle or listened to what I had to say. No investigations were launched by insurance, the manufacturer or the police. If anything, insurance and the manufacturer seemed like they were in a hurry to dispose of the vehicle, urging me to release vehicle where it was sent to after the crash to one of insurance centers. The collision warning light came on and the vehicle responded by hard braking and veering to the right, then the cruise control turned back on and accelerated into the rest stop, first bouncing up the curb and onto the dirt, hitting a sign on the passenger side then bouncing off a tree on the driver side and finally T-boned a parked boat on a trailer head on. The vehicle was a total loss
NHTSA complaint #11508517 — an unverified report by a vehicle owner.
The most recent complaints
In the owners' own words, exactly as filed with NHTSA.
Livonia, MI
ELECTRICAL SYSTEM
The vehicle experiences sudden, complete electrical power loss while driving at speed on highways and city streets or on the parking. All digital displays turn off, the engine shuts down, and power-assisted steering and braking are instantly lost without prior warning, presenting an extreme collision risk. The issue first occurred in August 2025 at approximately 48,000 miles and was taken to an authorized Hyundai dealer in Michigan for warranty repair. The dealer held the vehicle for over 30 days but failed to correct the defect. The identical power failure has continued and recently escalated to daily occurrences. A second Hyundai dealer (Pacifico Hyundai, Philadelphia, PA) diagnosed an intermittent open circuit in the engine wiring harness but Hyundai Motor America refuses to repair the vehicle under warranty, claiming 'outside influence' without providing evidence. Driving a hybrid vehicle that randomly cuts all power in live traffic is a life-threatening safety hazard. Hyundai Motor America has failed to rectify this critical safety defect.
NHTSA complaint #11755133 — an unverified report by a vehicle owner.
Livonia, MI
ENGINE
The vehicle experiences sudden, complete electrical power loss while driving at speed on highways and city streets or on the parking. All digital displays turn off, the engine shuts down, and power-assisted steering and braking are instantly lost without prior warning, presenting an extreme collision risk. The issue first occurred in August 2025 at approximately 48,000 miles and was taken to an authorized Hyundai dealer in Michigan for warranty repair. The dealer held the vehicle for over 30 days but failed to correct the defect. The identical power failure has continued and recently escalated to daily occurrences. A second Hyundai dealer (Pacifico Hyundai, Philadelphia, PA) diagnosed an intermittent open circuit in the engine wiring harness but Hyundai Motor America refuses to repair the vehicle under warranty, claiming 'outside influence' without providing evidence. Driving a hybrid vehicle that randomly cuts all power in live traffic is a life-threatening safety hazard. Hyundai Motor America has failed to rectify this critical safety defect.
NHTSA complaint #11755133 — an unverified report by a vehicle owner.
Luray, VA
ELECTRICAL SYSTEM
I purchased this vehicle pre-owned approximately two years ago and have since developed concerns about its reliability, particularly related to the electrical and hybrid systems. In hindsight, I suspect these issues may be part of the reason the original owner traded it in to a CarMax dealer. Shortly after purchasing the vehicle, I began experiencing recurring problems with the 12V battery, including frequent instances requiring battery resets. Interestingly, these issues were significantly less frequent during colder weather. More recently, as temperatures have increased, the problem has worsened considerably. For about the past month, the vehicle loses power and dies immediately after each drive once the ignition is turned off. This situation escalated yesterday when the “Check Hybrid System” warning light signalled while I was driving on a busy road. I had not encountered this warning before, but after researching the issue, I discovered that other Hyundai hybrid owners have reported similar problems. In some cases, these issues have led to dangerous situations, including vehicles shutting off unexpectedly while driving at highway speeds. While I cannot determine the extent of this issue across all Hyundai hybrid vehicles, the frequency of similar reports suggests a systemic defect affecting at least a subset of Hyundai Sonata Hybrid models. Regardless of scale, these battery issues present a significant inconvenience and a serious potential safety concern. I am requesting a formal review of this issue and guidance on potential remedies or corrective action.
NHTSA complaint #11745618 — an unverified report by a vehicle owner.
West Chester, OH
ELECTRICAL SYSTEM
The vehicle’s 12-volt electrical system repeatedly loses power within about 1 hour of sitting. The car becomes completely unresponsive (cannot unlock or start) and requires use of the built-in 12V battery reset button to restore power. This occurs frequently and makes the vehicle unreliable and potentially unsafe, as the car may become inoperable without warning. This appears to be an electrical system defect or parasitic power drain. The issue has been ongoing.
NHTSA complaint #11739503 — an unverified report by a vehicle owner.
Leesburg, FL
ENGINE AND ENGINE COOLING
See attached document for complaint.
NHTSA complaint #11730136 — an unverified report by a vehicle owner.
Spartanburg, SC
ELECTRICAL SYSTEM
Owned car since 09/2024 with 64K miles. Battery system (12V/hybrid system) has shut down and died 47 times since 04/2025 - no shut downs before then. Car with ~69K miles at that time. Dealer had car six weeks (05/17 to 07/05/2025) and it died “a number” of times and report that Hyundai claims this is “what the car is supposed to do.” Since 07/05 it has died 12 times just sitting in my driveway or the lot at work. This is NOT normal. Internet blogs show DOZENS of other Hyundai hybrid owners reporting the exact same issue. Car now with 75K miles and under warranty. Dealer will not replace battery system.
NHTSA complaint #11679975 — an unverified report by a vehicle owner.
Rehoboth Beach, DE
ELECTRICAL SYSTEM
This is on my 2021 Hyundai Sonata Hybrid Limited - for the 7th time the vehicle has been completely dead and unresponsive. I have had to gain entry to the vehicle using the manual key and press the "jump" button to get the vehicle to start. The Hyundai dealership ran a bunch of battery updates to the 12 volt battery several weeks ago and said that should hopefully fix the issue. Several weeks later on 07/19/2025 the vehicle was dead again. I had to use the key to manually gain entry and jump the car again. The dealership said that the 12 volt battery may need to be replaced and said that it is fully integrated with the hybrid battery system which is covered for 10 years/100K miles whichever comes first. I am still within the warranty period so hopefully Hyundai will fix the issue. From an online search, it appears this is not an uncommon issue with the Hyundai Sonata Hybrid. I am waiting on Hyundai for a fix and for .
NHTSA complaint #11676697 — an unverified report by a vehicle owner.
Mcdonough, GA
ELECTRICAL SYSTEM
What component or system failed or malfunctioned, and is it available for inspection upon request? RANDOM TOTAL ELECTRICAL FAILURE (DOORS WON'T UNLOCK, CAR UNRESPONSIVE) How was your safety or the safety of others put at risk? DIFFICULT TO GAIN MANUAL ENTRY TO CAR, PARTICULARLY IN DARK SITUATIONS Has the problem been reproduced or confirmed by a dealer or independent service center? NO, I HAVE TAKEN THE CAR IN FOR SERVICE TWICE AND THE ISSUE HAS NOT BEEN CORRECTED. THE CAR IS BACK AT THE DEALERSHIP NOW FOR A THIRD ATTEMPT. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? YES Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? NO As a reference: [XXX] Key Takeaways from the Thread: Several 2021 Hyundai Sonata Hybrid owners (and a few Ioniq and Elantra Hybrid owners) are reporting the exact same symptoms: Random total electrical failure (doors won’t unlock, car unresponsive) Requires manual key to enter 12V battery reset button inside vehicle restores power No error codes or permanent fixes from dealerships Issue occurs sporadically, making it difficult to replicate or diagnose Some dealers have replaced the 12V battery or DC-DC converter, but results are mixed No formal recall exists yet, despite growing reports INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA complaint #11672497 — an unverified report by a vehicle owner.
Bakersfield, CA
ELECTRICAL SYSTEM
Every day the car is dead, have to take the manual key out pop door cover off unlock car manually push the 12v reset button and hold fob to start/stop button for car to work again. Happens daily.
NHTSA complaint #11670129 — an unverified report by a vehicle owner.
Woodbury, MN
ELECTRICAL SYSTEM
12v battery dying randomly
NHTSA complaint #11663098 — an unverified report by a vehicle owner.
Portland, OR
ENGINE
Air flow check engine light alerted and source was faulty fuel injector which required replacement of 4 fuel injectors.
NHTSA complaint #11656895 — an unverified report by a vehicle owner.
Monterey Park, CA
ENGINE
Overheated engine alarm came on while I was on the freeway on a rainy day. Vehicle was towed to Hyundai dealership in which service technician found that the part preventing water from leaking into the muffler was broken. Hyundai dealership has ordered replacement part but it is on backorder. The broken part that needed replacement has been on backorder for close to a month and there is not an ETA of when the part will be received. Prior to the overheated engine alarm going off, cold air was blowing out of the vents even when the heat option was selected.
NHTSA complaint #11647194 — an unverified report by a vehicle owner.
Montgomery, OH
ENGINE
Coolant system leaks in to the engine or exhaust system, which is evident in white smoke exhaust and coolant level dropping. In my situation, I required an entire container of coolant to perform a daily commute, and the reservoir was empty by the time I made it to the dealership. Car is rendered undrivable due lack of coolant and engine overheating. My car was in the dealership repair facility for 6 weeks awaiting parts on back order due to nationwide shortage. A technical service bulletin has been issued for this manufacturer defect (23-EM-009H). Cost of repairs was roughly $2,300.
NHTSA complaint #11646538 — an unverified report by a vehicle owner.
Nottingham, MD
UNKNOWN OR OTHER
My 2021 Hyundai Sonata Hybrid seems to be leaking coolant into the exhaust system. Various reports online indicate that this is a consistent issue with 2020-2022 Hyundai Sonata Hybrid models. A lot of the reports indicate that owners have tried getting theirs cars repaired for the same issue I have a various dealerships all across the US, but either haven't had any luck or have had a temporary fix for the issue, which proceeded to occur again every couple of months. I personally have had my car inspected by my personal dealership and they have confirmed the issue and have mentioned that other owners have brought theirs in to be checked out, but haven't really had luck. I believe that Hyundai should take responsibility for this and issue a recall on the affected models. I bought the car in good faith hoping for reliability but haven't had it for even 6 months now and this problem is here. For safety or myself and others on the road, this models of the Sonatas need to be recalled and repaired IMMEDIATELY. For reference, here is a reference for the complaints people have made online regarding the vehicle: 1. [XXX] 2. [XXX] . (THE RESPONSES HERE ARE VERY DETAILED) [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA complaint #11636925 — an unverified report by a vehicle owner.
Nottingham, MD
ENGINE
My 2021 Hyundai Sonata Hybrid seems to be leaking coolant into the exhaust system. Various reports online indicate that this is a consistent issue with 2020-2022 Hyundai Sonata Hybrid models. A lot of the reports indicate that owners have tried getting theirs cars repaired for the same issue I have a various dealerships all across the US, but either haven't had any luck or have had a temporary fix for the issue, which proceeded to occur again every couple of months. I personally have had my car inspected by my personal dealership and they have confirmed the issue and have mentioned that other owners have brought theirs in to be checked out, but haven't really had luck. I believe that Hyundai should take responsibility for this and issue a recall on the affected models. I bought the car in good faith hoping for reliability but haven't had it for even 6 months now and this problem is here. For safety or myself and others on the road, this models of the Sonatas need to be recalled and repaired IMMEDIATELY. For reference, here is a reference for the complaints people have made online regarding the vehicle: 1. [XXX] 2. [XXX] . (THE RESPONSES HERE ARE VERY DETAILED) [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA complaint #11636925 — an unverified report by a vehicle owner.
Oak Park, MI
ENGINE
EHRS Coolant Leak- problem started in [XXX] when engine overheated. The weather in Michigan in inclement and being stranded in the intense cold can lead to loss of life. I had it towed to a Hyundai dealership that was unable to find the problem and in attempting to "find a leak" used the incorrect dye, necessitation transferal to another more competent dealership where the problem was diagnosed and was fixed with a replacement part. In December 2023 a TSB 23-EM-009h was issued by Hyundai describing this problem and issuing a part (Center Muffler). I was not informed and the problem recurred. currently this is the third episode and Hyundai after paying 95% of the previous cost, now only agrees to pay 85% and denies reimbursing me for the car rental. Warning lights appeared with all 3 occurrences. Hyundai should have issued a recall to obviate this. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA complaint #11635700 — an unverified report by a vehicle owner.
Woodbury, MN
ELECTRICAL SYSTEM
the car randomly goes into dead or limp mode and unable to start. need to jump start it to come alive. No codes shown once its jumstarted. it has happened at random on several occasions.
NHTSA complaint #11630638 — an unverified report by a vehicle owner.
Brentwood, CA
ELECTRICAL SYSTEM
When the vehicle is turned off the 12v Lithium battery will die. This is a intermittent occurrence that has happened approximately 7 times since [XXX]. Today is December 12, 2024. The car is currently at All Start Hyundai dealership in Pittsburg, CA. This dealership initially denied the car had a problem because they could not duplicate it in a 24 hour period and told me "the car is operating as designed". When I insisted they check the health of the battery, the service department would not do this until they received technical advise from Hyundai headquarters (HQ). It is a multistep process to get to the battery and requires removing the back seat. When HQ advised the battery check, the service department found the battery was swollen and needs to be replaced. I have found information on chat boards and YouTube where other car owners having the same issue. Why hasn't Hyundai HQ issued a recall and replaced all the batteries? The dealership has told me there are batteries in inventory in a warehouse in Los Angeles California, yet HQ has them on hold on back order status. What and why would the battery not be available for the cars having the issue? I believe a swollen 12v Lithium battery is a safety hazard and should be recalled. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA complaint #11630327 — an unverified report by a vehicle owner.
Columbia, SC
UNKNOWN OR OTHER
On three separate occasions, while going very fast (60-78 mph), the automatic emergency braking system turns on. The warning lights flash and there is some type of warning noise. I don't even know if it starts to break because it scares me so much, I just press the gas. It turns off within a couple of seconds, but that is not the point. If I didn't react so fast, I am unsure of what could actually happen.
NHTSA complaint #11627928 — an unverified report by a vehicle owner.
On three separate occasions, while going very fast (60-78 mph), the automatic emergency braking system turns on. The warning lights flash and there is some type of warning noise. I don't even know if it starts to break because it scares me so much, I just press the gas. It turns off within a couple of seconds, but that is not the point. If I didn't react so fast, I am unsure of what could actually happen.
NHTSA complaint #11627928 — an unverified report by a vehicle owner.
Yuma, AZ
ELECTRICAL SYSTEM
The BMS module within my cars hybrid system failed causing a parasitic drain on the hybrid battery. The dealership where the work was performed would have to be contacted for pictures. The hybrid battery system swole to a dangerously inflated level and did not produce any codes for an OBD reader to pickup. This has caused the dealership to turn my car away multiple times before finally performing the in depth inspecting required to verify battery swelling. This is a known problem throughout the internet I searched "2021 hyundai sonata hybrid battery dying every day" reddit has plenty of user with the same issues. I am not aware of who has inspected my battery besides the dealership. There was no warnings at all the only reason my battery was finally looked at is because of my persistence.
NHTSA complaint #11619346 — an unverified report by a vehicle owner.
at 24,000 milesYorba Linda, CA
ELECTRICAL SYSTEM
The contact owns a 2021 Hyundai Sonata Hybrid. The contact stated that the key fob was inoperable and after using the key to manually open the door. The contact stated that the vehicle failed to start while pressing the START/STOP button. The vehicle was towed to the local dealer, but the cause of the failure was not determined. The contact was advised that when the failure occurred, to start the vehicle, the battery reset button should be pressed before pressing the START/STOP button. The manufacturer was not contacted regarding the failure. The failure mileage was 24,000.
NHTSA complaint #11616027 — an unverified report by a vehicle owner.
Atlanta, GA
ELECTRICAL SYSTEM
On three separate occasions over the last two months, while driving, an alert comes on that says check hybrid system then the vehicle powers off. When this happens, you lose the ability to accelerate break steer, and I have been lucky each of those three times and that I was in a situation where there was not much traffic. I am not able to drive the vehicle at this time. I have reported the problem to Hyundai and they want me to drive the vehicle to the dealership for another check of it. They have looked at it once before and have not been able to diagnose a problem. It is unsafe to drive and they are not willing to assist in getting the vehicle to the dealership without me getting it over there.
NHTSA complaint #11612394 — an unverified report by a vehicle owner.
Atlanta, GA
ENGINE
On three separate occasions over the last two months, while driving, an alert comes on that says check hybrid system then the vehicle powers off. When this happens, you lose the ability to accelerate break steer, and I have been lucky each of those three times and that I was in a situation where there was not much traffic. I am not able to drive the vehicle at this time. I have reported the problem to Hyundai and they want me to drive the vehicle to the dealership for another check of it. They have looked at it once before and have not been able to diagnose a problem. It is unsafe to drive and they are not willing to assist in getting the vehicle to the dealership without me getting it over there.
NHTSA complaint #11612394 — an unverified report by a vehicle owner.
Antioch, IL
ENGINE
Coolant leak acting like blown head gasket. Coolant was leaking into the exhaust system. Defective EHRS system
NHTSA complaint #11609725 — an unverified report by a vehicle owner.
