Table 1 shows one common electrical system related problems of the 2021 Hyundai Sonata.
| Problem Category | Number of Problems |
|---|---|
| Electrical System problems |
My 2021 Hyundai Sonata limited hybrid 12v battery has started to die randomly. My car is currently with the Hyundai dealer to confirm if this will be a warranty claim. Searching online, I have found other posts of people complaining about a similar issue with their 2021 Hyundai Sonata hybrid.
Car sits several days at a time. Door locked. 12 volt auxiliary battery goes dead within 60 minutes after driving 60 miles. Happened 6 times in last 6 weeks. Battery is lithium. Dealer looked at car sept 8. They did cursory check and said my rodent deterrent caused issue. After driving 60 miles. Turned rodent deterrent off. Still have issue. Car resets the 12 volt battery nearly daily. Lithium battery if bad can blow up and cause vehicle fire. Car is parked in car port next to house. If fire, it burns up my house also. This is fire hazard. If the battery is bad, it must be fixed. Car under 10 year 100,000 mile bumper to bumper warranty. I need car fixed. Not just looked at. This is fire hazard till it is fixed,.
2021 Hyundai Sonata with approximately 39,000 miles. On 8/21/2025, the dashboard displayed the following message "shifter system malfunction! service immediately" when the warning appeared, the vehicle shifter button would not function, creating a traffic safety risk. History: dealer service history shows the transmission was replaced on the vehicle under warranty on 08/30/2021 with 2,212 miles with no campaign/recall issued. Dealer states there is no recall campaign on this vehicles specific VIN # and NHTSA currently shows no open recalls for this vehicle. However, Hyundai advertises an 8-speed dct safety recall for the same year, make and model, and describes this identical issue, but has left this vehicle's VIN# out of scope for this recall, which is continuing to demonstrate the same issues. Current dealer/manufacturer response: on 9/4/2025, the dealer declined warranty or recall repair unless the fault was active on their diagnostic scan at the moment the scan was performed. A photo was provided to the mechanics of the dashboard showing the transmission service warning, with current mileage. The dealer advised there were no diagnostic log history showing the transmission error code even with photographic proof and attempted to return the vehicle to me. I have rejected the return of the vehicle and advised that this needs to be escalated, because if logs are not appearing, this is even a bigger cause for concern and that the vehicle is a safety hazard. Concern: because this vehicle required an early transmission replacement and is now exhibiting new transmission/shifter warnings, I am concerned the failure relates to the known transmission/shifter recall on this model and that the recall scope and/or remedy is incomplete for the affected vehicles including my VIN #. It is also possible the dealership is attempting to run out the warranty which expires in 3 months. Vehicle, photo of the warning, and service records are available for inspection.
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 .
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.
12v battery dying randomly.
The buttons to the door locking and unlocking don't work unless I open and close my door a few times. The same thing with the back windows. But after you do the trick and use the intended button once, it stops working and have to repeat the entire process over again. Which is not safe especially when the car is in motion, I am not able to use those buttons at all.
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.
On 5 separate occasions the car has shut itself off while driving. After the first 2 times the car was taken to the dealership where they found nothing wrong and told us to replace the battery. The battery was replaced by the dealer and within the next two weeks the car shut itself off while driving 3 more times. The car will always start back up again right away. This is a very dangerous situation.
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.
This car has two problems. 2 weeks I was driving on the highway. All the sudden the shutoff and lost all power on the car. Thank god I pulled to the side of the road safely. Turned the car off and turned it back on. The car started to run normal. I took it to mechanic. They scanned the car with their computer. Said the car has no problems. Tested the battery and all other components. No problems found. This happened again yesterday on the highway driving. Car engine shuts off again. The car has engine problems as well. But Hyundai denies to address it.
2021 Hyundai Sonata 59,850 miles rpm jumps to around 1,300 at zero miles on occasion. If I am stopped, at a red light or behind other stopped autos, the vehicle jumps forward when I take my foot off the brake. Because this happens quite often, I am aware of this and keep my foot on the brake until other vehicles are out of the way to avoid bumping into them. When this happens, I can cruise at 30 miles per hour without having my foot on the accelerator, I can slow down or stop by applying the brakes but the engine rpm stays at 1,300. If I stop and shut off the vehicle and restart, the operation goes back to normal but occurs again later. The Hyundai dealer has had the vehicle back 9 times but the issue continues. The first few times, they could not find an issue, I returned to the shop when this was happening and the service manager and a technician observed this condition, the egr valve was replaced. Was ok for a bit but condition returned, the computer was then replaced. Condition continued. Brought the vehicle back and a scan was done and system “re-learned. After a short time the condition returned. Went back to the service center and they did another scan and another re-learn. Condition returned 4-5 days later. Problem still not resolved. Have 59,850 miles on the vehicle, warranty expires at 60,00 miles. This started around July 1, now October 5. Waiting for a loaner so the service center can drive it around until the situation occurs and they can bring it in immediately for diagnosis. This is the same issue as reported for the same year vehicle in July 2022.
When the vehicle is turned off the 12v lithium battery will die. This is a intermittent occurrence that has happened approximately 7 times since September 28, 2024. 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.
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.
Blower motor on 2021 Hyundai Sonata sel stopped working. Same issue happened on my 2020 Hyundai sel and currently waiting on my 2020 Sonata to be fixed. Hyundai technician said the wiring harness had a crack and it’s why my 2020 Sonata’s blower motor stopped working. It’s now three months since they diagnosed and ordered the wiring harness but supposedly it’s still on back order and I’m left with a hot car this entire summer and possibly a cold car come this winter. Now it looks like I will have the same issue with my 2021 Hyundai sonta.
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.
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).
Randomly the car will get a message when driving starting “ check hybrid system. Turn engine off” and the car isn’t able to accelerate when this happens. When you cut the engine off the car is unable to start again until it is jumped. I’ve confirmed the battery isn’t the issue however something with the vehicle is wrong. There are many accounts of people online dealing with the same issue.
Driving on the freeway when we got a notice on the dash that we needed to pull over and the vehicle shut down due to a fuse,/battery issue.
In June 2024, I was driving my vehicle when I started to smell burning from under the dashboard. As I continued to drive, the smell got worse, and on my way to the dealer, my air conditioner stopped working. I took my car back to the dealer for service, and several days later, I was told that my car needed a hardness connected to several components in the engine compartment. I remember while I was dropping off my car at the dealer, one of the service advisors told me that it was good. I drove to the dealer because the car could have gone on fire. It's now six months later, and they have not fixed my car. I was told they're awaiting parts from korea to complete the fix. My concern is that this part can cause a fire. Why did Hyundai not recall these vehicles? Hyundai knows about the problem. I was told that I'm not the only one waiting; supposedly, there are 100's more customers waiting for this part.
My car will power off randomly, or will seem as though there is no power. I have to revert back to the manual key to enter the vehicle and hit the 12vlt reset to power it back on. This happened at least 3 times. Once while operating the vehicle, and twice while the vehicle was left parked. This is not a low battery issue as, the car will only do this occasionally, and not every time I enter and turn on the vehicle. There is no error code to follow this mishap as all power goes out and the dealer maintenance has nothing to work with.
Integrated 12v battery in hybrid system keep draining out. I have to manually open the car and reset it every time in order to be able to drive.
My battery has died twice, so dead that I can’t even unlock to car with the remote. The first time I had it jumped and took it to the dealership where they were unable to find anything wrong with it and they told me if it happened again to have it towed in so they could diagnose it while the battery was dead. So that happened again and I had it towed in to the dealership in early April. It’s now July and they still have my car and don’t have a diagnosis yet. They have had their field engineers out to run all sorts of tests, but nothing yet. Today they told me they have 3 Sonata hybrids there with the same issue as mine.
The battery dies randomly and requires the physical key to unlock the door. It is a hybrid, so it has a 12 volt battery button that jumpstarts the car. While driving the vehicle, the battery meter on the dashboard will show a near-full battery and then a near-empty battery within a few minutes. This vehicle was bought brand new from a Hyundai dealership and for the first 2 years, there wasn't an issue. The past few months, the battery issue started.
The vehicle, after parking, is nonresponsive to the key fob, nor will it start. This can happen at anytime and anywhere. Dealer said "it is possible the integrated 12v battery into the hybrid battery may be faulty. No codes or tests can confirm the issue. The dealer said the key fobs tested ok. " my wife works late at night in a dark area, this has happened 2 times at her place of work and we are concerned for her safety as she has to wait outside for a tow truck to tow it to the dealer. The first 3 times it occured, this issue started around March of 2024, and repeated every 30-45 days. Now it has happened 2 more times in the last week. No warning lamps or indications of problems. The windshield has distortion within the glass and is not a clear view. It is as though you are looking through the heat of a jet engine trying to focus on what is on the other side. This is a major distraction while driving, reading the heads up display in the car, reading street signs and general navigation of pedestrian and other vehicle traffic. There is no aftermarket film or materials on the windshield. The door handle on the drivers side has a cover plate over the hole where a manual key could be inserted. As a construction worker I have very strong hands and I have a difficult time removing the cover plate. The last time I removed the plate I cut my hand on the interior part of the handle as the cover plate popped off. That is how hard the plate is to remove. My wife cannot remove the cover plate on her own. This system is in place for the manual use of the hidden key inside the key fob to be able to open the door in the event of a power failure of the vehicle. Which has now happened randomly 5 times.
The battery dies randomly (like I have to open the car with they physical key to access the car dead) there isn't a pattern. I have taken it to the dealership and they can't diagnose it because they cant replicate the issue and say nothing is wrong. Sometimes the car dies while I'm inside and just having lunch while the car is off.
Infotainment center won't switch to radio. No signal for am/fm or satellite. Then hvac system stopped blowing. No defrost, won't blow heat or ac. Blower motors been tested and works, blower motor resister replaced. Everyone I talk to is saying it's an electrical, connection issue.
Fuse box has a defect causing the ac blower motor to intermittently not work. Appears to be the result of loose connections between the fuse box and the fuse itself. The receptacle for the fuse is clearly burnt/melting, and appears to pose as a fire hazard as a result. The car is currently in the shop for repair on this part, but won't likely be fixed for a month+. I do have photos of the damaged parts, should it be requested. The car was taken into a Hyundai dealership for repair work in November 2023, and I was told the fuse had blown but that they fixed it. I was never told about the box appearing damaged/melting at that time, or this being a common problem. It worked again till July 2024. Car was just dropped off 9/3, due to backlog of cars at dealership. The only symptom of issue was the ac blower motor would stop working at random. It would turn back on/off while driving. This seems to be due to the loose connections between fuse box and fuse.
My 2021 Sonata hybrid limited has been in the shop for over 3 months. At least 4 times while driving on city streets, I'd receive an error stating problem with hybrid system please turn off vehicle. Car would go into limp mode giving me just enough power to pull off to the side of the road (if possible), then completely shutdown. Fix action is to hit jumpstart button to get the power back to the vehicle in order to power it on again. After those issues battery constantly died and I had to use the physical key to open the door and hit the jumpstart button to get power. Dealer (Hyundai jim click east, tucson, az) couldn't find an issue initially stating they could not replicate what I was experiencing. But eventually my patience ran thin and they finally identified a voltage error while in the service department. The rep informed me that the issue lies with the 12v battery which is integrated into the hybrid battery (stupid design). Service tech had to order a 12v battery from korea (after dismantling the hybrid battery and sending the pics to Hyundai for approval). This was July 18th. Still waiting on the parts, no updates at this time. There was another Sonata hybrid limited like mine also at the dealership for the same issue. This vehicle had been there since June. They were able to get a new battery for that vehicle, however after a week the same issues reoccurred. I've noticed on reddit forums that many 2021-2022 Sonata hybrid limited owners have been experiencing the same issue, with the same long wait times from Hyundai hq regarding a solution. At this point I believe it'd be best to open an investigation as there it's been difficult for the dealership and the owners to get any answers from Hyundai regarding this issue. I'd also suggest a recall for this vehicle as it's clearly a widespread problem and hopefully that will give Hyundai the kick in the ass needed to actually take this seriously.
The car keeps randomly dying (not during driving "yet") it happens at least once or twice a week of where I go to ride my car and it is completely dead, I have to unlock the door using the key fob manually and push the "reset 12v battery button" inside the car. I have tried to have Hyundai service repair the issue or at least tell me what's wrong but no hope as they can never replicate the problem. I am seeing alot of users posting online on numerous web forms (reddit,facebook. . Etc) that they are having the same exact issue as me for the same exact model of my car, with also no help from the dealer on the matter. This must be a defect at some point and would greatly appreciate if NHTSA can help push this issue to the dealer.
The vehicle has been turning completely off after use for over a year now. At first it would happen every now and then at the beginning and all you'd have to do was restart the car manually. Now every time the car is turned off it needs to be restarted manually now. The car will also shut itself off while you are driving. It will tell you something is wrong and then won't let you get over 15-20 mph. If you are on a neighborhood, it's less dangerous for this to happen where you can pull over and turn off the car and restart it. But I have seen other post that they've started to malfunction on the freeway and highways before. My car is a 2021, but recently I've seen 2023 models are doing this as well. I know some people on the internet have gotten their car fixed by replacing a back logged battery. It took some people over a year to get it diagnosed correctly and 6 more months to get a new battery. I assume this is also what is wrong with my vehicle. It is in the shop right now, but we have not gotten an answer back even htough it's been there for 10 days. The car app has also indicated that the car has not been turned on since we left it there.
Unknown.
So for the past year and half my cars left turn signal has been working intermittently. It just stops working and then it starts again. I have taken it to the dealer many times they changed out signal assembly I have taken many videos show proof. I am told at the dealer if you dont bring it in when it is not working then they cannot do anything even if I have video proof documenting this issue for the past year this is a serious safety issue that must be addressed. My next step is to contact Hyundai directly hopefully you can investigate this issue. This is very dangerous.
After 9 months of ownership, on at least five (5) instances, the car has the following things happen at the same time: 1) all warning lights on the dashboard activate, 2) the battery discharge warning light activates, a loss of power steering, no speedometer, no cameras (rear or front), no ac, and all the safety functions are disabled including but not limited forward collision warning, parking collision warning, automatic emergency braking, lane departure warning, rear cross traffic warning. Yes, the car is available for inspection upon request. Safety is at risk by the loss of power steering and the deactivation of all safety functions. After each instance, the car has gone back to the manufacturer's dealer for inspection, they believed it might be an electrical issue after scanning for fault codes, but after 5 times, the dealer has not yet diagnosed the issue.
Hello the car shut off on the freeway while driving. The display lit up light a xmas tree including the forward collision warning. I though this was an isolated incident. It has happened now numerous times. The car even braked on its own then shut off while turning in the middle of a busy intersection. There are several reports of very similar symptoms on edmonds under reviews. This car is dangerous. I have contacted Hyundai twice now.
On Wednesday, October 6th, I was driving full speed (65mph) on a major highway. Multiple lights on the dashboard came on. The lcd display screen for music, apps, etc. Went black. More lights came on and others went off on the dash display. I let off the accelerator and steered the car. The fuel efficiency was wilding jumping back and forth. Soon enough, all the lights went back off, but the mileage gauge (fuel efficiency) continued to jump wildly. The brakes seemed to respond differently- almost as if there was a delay between me pressing the brake and the brakes catching. When I needed to accelerate, the car seemed to be having trouble switching between the electric and gas motors. I was able to drive to a safe location and shut the car off. This was terrifying, as the car's computer system or electrical system clearly failed, even if temporarily. The car was taken to the dealership immediately. The car's mileage is under 4, 500 miles and was purchased in February 2021. There have been other small issues but never anything like this. The display screen has gone black before a few times, my cell phone won't connect (even manually and it's properly connected, working seamlessly other times). In those cases, I shut the care off and restarted it to fix the issue. However, this new incident is terrifying and unacceptable. Including photos taken that show impossible fuel efficiency as only evidence I could safely capture.