2020 HYUNDAI SONATA Electrical System Problems

I have taken my vehicle to a certified Hyundai dealership multiple times due to intermittent starting issues. The car will unlock remotely, and the lights and electrical components will turn on, but the engine will not start. When this happens, I press the ignition button to turn the vehicle off and then try again. Sometimes it eventually starts, but there have been several occasions when it would not start at all, forcing me to call for a tow or have the battery jumped. This issue occurs most often in cool or cold weather. I had a brand new battery installed at the dealership in July 2025, yet the problem has continued. I have been dealing with this for over a year and have even been stranded out of state in below-freezing temperatures. Each time I bring the vehicle in, the dealership states they are unable to replicate the issue while...

While stopping at a major highway intersection on [XXX] for a red light vehicle stalls and will not start back up while everyone else continues at a 55 mph mile an hour passing me on each side! This happened more than 6 times . While you’re stuck in intersection,you have to keep trying to start the car eventually it will start . Apparently it is EGR valve and is a very common problem. IT IS NOTED IN THE common problem for this year making model and the repair cost is in the range of $1600 even the dealership said it is a very common problem. They have been experiencing it. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Wiring harness under fuse box is not making a consistent connection and is causing the blower amp to overheat and disconnect. When this happen, cabin air doesn’t blow and the front and rear defrost stops working. The only way to make the blower engage is by removing the fuse box cover and tapping the 30 amp fuse things. I’ve taken my car to the dealership for this specific problem 5 separate times, and it was supposed to be corrected. Due to this poor connection, I am now about $1200 into repairs / replacing parts that aren’t the root cause. I am not taking my car back to the dealership for a 6th time to have it “fixed” but the service guy looked me in the face and said “you should trade it. We see this issue all the time in sonatas and elantras. It won’t be fixed”. I’ve replaced the...

The ac blower keeps going out I looked it up and a lot of people are having the same problem my ac keep having to buy blowers and they last 1 week before they stop working and they are not cheap my blower keeps going out and my electric in my car keeps messing up when I try to put the ac up it goes up then goes down I don’t know what’s wrong but I looked it up and a lot of people have the same problem

Without warning, symptoms of the A/C blower not working first occurred a little over a month ago. The fan just stopped blowing altogether (no cold or hot air). After turning the car and the A/C system on and off several times, it began working again and that was it. This past week, the same issue occurred intermittently over 3-4 days. The A/C blower did not come on for a day, the next morning it was functioning, that evening it stopped blowing again, and this went on for several days. Research of the symptoms via YouTube and many online forums, and most importantly confirmation through visual inspection of the fuse box, confirmed that the BLOWER fuse is burning so bad it has melted the connecting port in the fuse box. Whatever the electrical malfunction, the fuse burning and melting is disrupting the connection and ultimately the A/C blower itself. In the...

The HVAC blower motor and related electrical components (including the fuse box, wiring harness, or control module) have malfunctioned. The system either fails to operate entirely or works only on low, with unpredictable surging airflow. These components are still installed in the vehicle and available for inspection upon request. For the past five days, my family has been driving without a functioning air conditioner in extreme Oklahoma summer heat. This is not only uncomfortable but unsafe, especially for my young child who regularly rides in the vehicle. In addition, without reliable airflow, we are unable to defog the windshield in humid conditions, which significantly reduces visibility and increases the risk of a crash. The inability to regulate cabin temperature and airflow poses a serious safety hazard. Yes, the issue has been observed by the dealership during service visits. However, Hyundai has denied goodwill repair assistance and has not formally acknowledged...

So I was driving down the highway and I went to pass a car, (I never get close when passing) I was probably at least a quarter mile away from the car I was passing. I have every safety feature turned off, as I have, since buying the car almost 2 years ago. All of a sudden, I’m not sure if my sensor was off or what, but I’m assuming it thought I was too close to that car and it just started swerving all over the highway. I went left/right 4 times before I was finally able to regain control, I couldn’t couter-act the swerves, nor could I hold my steering wheel straight to stop them. Luckily there were very few people on the highway as it was early in the morning. Had the time of day been different, I probably wouldn’t be here today, and some others probably...

My 2020 Hyundai Sonata has a recurring defect in its engine or transmission, causing sudden deceleration to ~10 mph without warning, often on major highways, with warning lights (check engine, ESC, traction control, etc.) flashing seconds before the car decelerates. This forces me to swerve off busy roads, endangering me, my passengers, and other drivers. Near-misses with traffic pose an extreme safety risk, causing significant emotional distress. The car, at a Hyundai dealer since April 21, 2025, is available for NHTSA inspection. The issue began in January 2021, five months after purchase, with all the warning lights appearing during incidents along with rapid deceleration. The Hyundai dealer confirmed the problem in seven repair attempts (January 2021, December 2021, January 2022, November 2024, February 2025, and twice in April 2025) but never properly diagnosed or fixed it, citing no consistent diagnostic codes. Only the dealer assessed it; no inspections by Hyundai’s...

My 2020 Hyundai Sonata has a recurring and dangerous defect involving sudden deceleration while driving. Without warning, the car abruptly slows to ~10 mph—often on the highway—while numerous dashboard warning lights activate. This poses an extreme safety risk to me, my passengers, and other drivers, as it forces me to maneuver off the road to avoid being hit. The issue began in January 2021, still with less than 4,000 miles and just five months after I purchased the car new. It has occurred repeatedly and unpredictably since then. I have taken the vehicle to a Hyundai-authorized dealer for repair on five occasions (January 2021; December 2021; January 2022; November 2024; and February 2025), but the problem has never been properly diagnosed or fixed. In November 2024, the issue occurred immediately as I drove off the dealer's lot, having been assured the vehicle was repaired and safe to drive. The most...

My 2020 Hyundai Sonata has a recurring and dangerous defect involving sudden deceleration while driving. Without warning, the car abruptly slows to ~10 mph—often on the highway—while numerous dashboard warning lights activate. This poses an extreme safety risk to me, my passengers, and other drivers, as it forces me to maneuver off the road to avoid being hit. The issue began in January 2021, just five months after I purchased the car new. It has occurred repeatedly and unpredictably since then. I have taken the vehicle to Hyundai-authorized dealers for repair on five occasions (January 2021; December 2021; January 2022; November 2024; and February 2025), but the problem has never been properly diagnosed or fixed. In November 2024, the issue occurred immediately after I picked the car up from the dealership when they told me it was fixed and ready to drive. This most recent occurrence (February 2025) before tonight's...

My 2020 Hyundai Sonata SE (82931 miles at the time) has experienced repeated issues with the front passenger window. The window would get stuck while attempting to operate it, accompanied by a loud, crushing noise. Upon visiting the dealership, I was informed that the issue stemmed from the window regulator, which had failed internally and required replacement. Additionally, my girlfriend, who owns a 2020 Hyundai Sonata SEL with approximately 31,000 miles, is now facing the exact same problem with her vehicle’s front passenger window. After conducting research on online forums, I discovered that several other 2020 Hyundai Sonata owners are reporting similar issues with their window regulators. This suggests that the problem may not be isolated to just one or two vehicles but could point to a potential widespread defect. Although this issue primarily affects the operation of the window, it could lead to safety risks if the window gets...

My Passenger window fell down and will not go up, It is available for inspection upon request. Safety Risk is that the window is being help up by tape and if it falls all of a sudden while driving could break the glass and spread inside as well as cause object to fly out of the vehicle. This has not been inspected by the manufacturer or anyone No warning lamps or messages. I put my window down and then it never went back up and motor was just running and probably made it worse

I believe the transmission malfunctioned as I reached 60 MPH / 4000 RPMs on the highway when it suddenly did not want to accelerate past that. The more I stepped on the gas pedal, the more it slowed down. I attempted to use the paddle shifters to shift up or down, but I was unable to shift up and shifting down did not allow me to accelerate past 4000 RPMs. The flow of traffic was faster than I could keep up with, and not being able to accelerate made it unsafe to be on the highway. I had to pull over, and get off of the highway. I found that others have reported this same issue online with the same make/model/trim, but I have not had time to take it in to be looked at. No warning lamps, messages, or other symptoms prior to failure. I only noticed when I...

Blower motor stopped working. Same issue has now happened on my 2021 Hyundai Sonata Limited. I have been waiting now three months to have 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 Limited leaving me with two cars without A/C or Heat.

Improperly seated strip fuse High Resistance Connection on the IG-2 40amp blower motor fuse receptacle causing melting of plastic fuse box components and ultimately failure of blower motor circuit and potentially loss of other circuits. Loss of blower motor leads to loss of cabin HVAC as well as loss of front windshield defrost ability during adverse driving conditions. Not only does this pose a potential electrical fire hazard, but a safety hazard due to inability to clear windshield from loss of defrost feature. Brief research finds this to be a very common problem with these vehicles. Manufacturer's recommendation is complete replacement of engine bay wiring harness. Problem begins as intermittent, but leads to total circuit failure over time if not identified.

Multi fuse controlling the A/C blower has burned out 3 times in the past year.

I was driving on the interstate when I heard a click from the back of the car. The gas gauge started to move downward as if I was losing gasoline. It eventually stopped and started moving back up, past where it was when it started decreasing. A little bit later the check engine light came on and the car started driving very sluggishly. I took the car into the Hyundai dealer and they found that the backseat was clicked out of place and a sensor was unplugged. This issue has since occurred multiple times. The back seat will pop out of place, the gas gauge will move beyond the gas that is in the tank, and finally the check engine light will come on and reduce the performance of the vehicle. The gas tank appears to be swelling and pushing up against the back seat which is causing it to...

Vechile shut down completely on the highway, engine's been replaced twice, Catalytic converter, Turbo was replaced three times, Battery oxygen sensors, timing belt all have been replaced, Along with my wireless charger and Both heaterhouses and splash guard. I recently had my vehicle SERVICED Thirty five hundred miles after NEW engine install The dealership serviced my car didn't reset my service indicator 3 weeks later, my vehicle without warning said Engine overheated, so I pulled over immediately that display went off. My actual thermostat stayed under the center line in between cold and hot. I contacted the dealership and got my vehicle into BE inspected At that time, they said my coolant level was low and both heapeer. Hoses needed to be replaced and my engine needed to be flushed and refilled. I had those services completed. I picked up my car 5/24 it was OK on 5/25 My service...

Defrost doesn’t work because harness melted and blew a fuse

While driving my cars a light starting blinking and my engine light came on and the car lost power This has happened on at least 3 occasions and I had to pull over upon starting the car after a few hours all returned to normal I reported this to dealer and they could not find a problem

I took my vehicle into the dealership when it was under 12,000 miles for another issue and mentioned a problem with the headlight on the right fogging up with moisture. I was immediately told that this had to be seen with their eyes because light cost more than $1,000. It has continued for over 1 1/2 years. Early this month, I took a picture at night and in the morning. The service manager wanted to add another hoop; can you get a picture of the water in it? The water is droplets on the light, decreasing visibility on the road. Pictures are attached. There is one picture that shows the left headlight with no issue.

The AC Fan in my car quit working. Took it to a repair shop where I was told that the AC Blower Motor went bad. The blower motor was drawing too much amps and caused the blower motor fuse to melt into the wiring harness for the blower motor along with melting several other fuses nearby including the fuse box. The cost to repair this correctly fixing and addressing all parts damaged was $5000. Because my vehicle is out of warranty due to mileage I contacted Hyundai who stated that I had to go and pay another diagnostic fee at a Hyundai Dealership to have them look at it. They continued to tell me that the vehicle was out of warranty but would not assist in providing information to get the issue resolved at no cost to me.

The contact owns a 2020 Hyundai Sonata. The contact stated that while her husband was driving 75 MPH, the brake warning light appeared on the instrument panel as the vehicle began to hesitate upon depression of the accelerator pedal. The contact stated that the vehicle decelerated to 20 MPH as her husband pulled to the side of the highway and turned off the vehicle. The contact called the dealer and was given suggestions on how to correct the failure; however, none of the options worked. After some time, her husband restarted the vehicle and the vehicle resumed normal operation. The next day, the contact stated that the brake light returned upon start of the vehicle. The manufacturer was not notified of the failure. The vehicle was not repaired. The failure mileage was approximately 19,000.

I first begin having an issue with the idle speed. It would jump up to 1,500 RPM, which is twice the normal 750 RPM level It started almost from the very beginning when I purchased this car new in early 2020. I mentioned it at first oil change at dealer at 3,500 miles. I was told it was normal. In the beginning it would come and go. Sometimes not happening for weeks in-between episodes. Then it started to have the check engine light come on after it would happen and stay on. I took it back while light was still on and they kept the car for several days. Said it was the EPV valve and replaced it. Car operated fine for a few days then started up again. It also started to idle up and down from 1500 down to 500 in a rapid succession. I was able to...

Driving, car started making a weird sound followed by a warning light on dashboard with dinging sound to correlate... car became difficult to gas, vehicle motion was lagging where I just knew I had to pull over Bc this car was going to literally stop began to slowly (Bc that’s all car would allow) to proceed forward and I was forced to come to a haunt as I pulled onto side of highway. I then could no longer move it. Turned car off for minute then returned to try to start again, car would not accelerate at all nor turn on fully.. I was forced to wait hour to get a tow... took to shop, no problem such was found , car started & ran again ... this is 3 days later the car again continued the same exact pattern & I was unable to drive any further and forced...

THE VEHICLE'S FUEL GAUGE (TYPE C) DOES NOT ACCURATELY ADJUST FOR CHANGES IN THE AMOUNT OF GAS IN A TIMELY MANNER. IT NORMALLY TAKES 2-3 DAYS FOR THE GAUGE TO MOVE TO FULL TANK EVEN THOUGH IT IS FULL. SAME PROBLEM FROM 1/4 TO 1/2 TANK, ETC. FOR EXAMPLE, I NOTICED THE PANEL SAID I HAD 11 MILES TO EMPTY ON FRIDAY. THE GAS GAUGE SHOWED OTHERWISE. I WASN'T NEAR MY USUAL FILL STATION, SO I PUT 5 GALLONS OF GAS IN THE CAR. IT IS NOW WEDNESDAY (5 DAYS LATER). THE GAS GAUGE MOVED SLIGHTLY YESTERDAY TO ALMOST 1/4 TANK, BUT THE FUEL TANK WARNING WENT FROM 11 TO 0 MILES LEFT TO EMPTY (SEE ATTACHMENT). I DROVE ON THE HIGHWAY EACH DAY AND IN THE CITY. I PURCHASED THIS CAR JULY 2020 WITH A FULL TANK. THIS PROBLEM BECAME EVIDENT IN AUG 2020. AFTER REFILLING THE TANK, THE...

FOLLOWING A FIRMWARE UPDATE TO THE OBC FOR A RECALL, THE VEHICLE TRANSMISSION NOW HAS A SEVERE DELAY RESPONDING TO DRIVER INPUT. THE TRANSMISSION IN THIS VEHICLE HAS ELECTRONIC SHIFT WITH PUSHBUTTONS. PREVIOUS TO THE FIRMWARE UPDATE, THE TRANSMISSION WOULD RESPOND INSTANTLY TO DRIVER INPUT FROM THESE BUTTONS. FOLLOWING THE FIRMWARE UPDATE, THE TRANSMISSION TAKES TWO SECONDS TO RESPOND. THIS DELAYED ACTION PROHIBITS DRIVER EMERGENCY SHIFTING, CREATING SEVERE RISK OF AN ACCIDENT. IN MY VEHICLE, I RECENTLY WAS ALMOST INVOLVED IN A TRAFFIC ACCIDENT WHEN THE DELAYED RESPONSE FROM THE TRANSMISSION CAUSED MY VEHICLE TO REVERSE INTO THE OPPOSING LANE OF TRAFFIC AS ACCELERATION WAS ATTEMPTED THINKING THE VEHICLE HAD SHIFTED INTO DRIVE. UPON ENTERING THE ACTIVE OPPOSITE LANE OF TRAFFIC, EMERGENCY ACCIDENT AVOIDANCE WAS PROHIBITED BY THE DELAYED RESPONSE OF THE VEHICLE SHIFTING INTO 'DRIVE' IN ORDER TO MOVE THE VEHICLE FROM THE OPPOSITE LANE OF TRAFFIC. PREVIOUS TO...

I OWN A 2020 HYUNDAI SONATA. I PURCHASED THE CAR ON JANUARY THIS YEAR THE MILES IN THE CAR IS 700 MILES. A MONTH AFTER THE CAR STAR GIVING ME PROBLEM WITH BREAK. SOMEHOW THE CAR APPLIES THE EMERGENCY BREAK BY ITSELF AND DOESN'T WANT TO MOVE. WHEN I DRIVE THE CAR SUDDENLY STOP BY ITSELF AND GIVING ME MESSAGE LIKE: TO MOVE THE CAR PUT YOUR SEAT BELT, LOCK ALL THE DOOR EVEN WHEN I HAVE MY SEATBELT AND DOORS ARE LOCK THE CAR DO THAT WHEN EVER THE LESS I EXPECTED. I TOOK THE CAR THREE TIME FOR REPAIR AND UPDATE AND THE CAR GIVE ME THE SAME PROBLEM. THE DEALER GAVE ME A LOANER ANOTHER 2020 SONATA AND HAVE THE SAME PROBLEM. THIS IS A VERY DANGEROUS ISSUES BECAUSE IF IS RAINY OR SNOWING. THE DEALER DOESN'T FIND ANYTHING WRONG WITH THE CAR WHEN THEY DRIVE THE...

TL* THE CONTACT OWNS A 2020 HYUNDAI SONATA. THE CONTACT STATED THAT WHILE DRIVING AT VARIOUS SPEEDS, THE PASSENGER'S SIDE BLIND SPOT DETECTION SYSTEM FAILED TO ACTIVATE. THE CONTACT ALSO STATED THAT THE FORWARD COLLISION WARNING LIGHT INTERMITTENTLY ACTIVATED WHILE STOPPED AT A RED LIGHT. THE CONTACT STATED THE REAR BRAKE ASSIST ACTIVATED INTERMITTENTLY ON SEVERAL OCCASIONS. THE VEHICLE WAS TAKEN TO NASSIEF HYUNDAI LOCATED AT 1059 OH-46 NORTH, JEFFERSON, OH 44047, AND PRESTON HYUNDAI OF SHARON LOCATED AT 1251 E STATE ST, SHARON, PA 16146, WHERE THE MECHANICS WERE UNABLE TO DUPLICATE FAILURE. THE VEHICLE HAD NOT BEEN DIAGNOSED NOR REPAIRED AS OF YET. THE MANUFACTURER HAD NOT BEEN INFORMED OF FAILURE. THE FAILURE MILEAGE WAS APPROXIMATELY 623. *BF *TR

TL* THE CONTACT OWNS A 2020 HYUNDAI SONATA. THE CONTACT STATED THAT WHILE DRIVING AT APPROXIMATELY 55 MPH, THE VEHICLE SHIFTED INTO SAFE MODE AND LOST MOTIVE POWER. THE VEHICLE WAS TAKEN TO ST. CHARLES AUTOMOTIVE LOCATED AT 5601 VETERANS MEMORIAL PKWY, ST PETERS, MO 63376, (636)441-4481 BUT WAS NOT DIAGNOSED NOR REPAIRED. THE MANUFACTURER WAS NOT CONTACTED OR INFORMED OF THE FAILURE. THE APPROXIMATE FAILURE MILEAGE WAS 1,500.