2021 Hyundai Sonata Visibility Problems

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 failure creates a severe visibility hazard. During acceleration from stop lights and stop signs, the vehicle emits massive, thick clouds of white glycol smoke. The smoke is so dense that it completely obscures the driver's view of trailing vehicles and prevents following drivers from seeing the roadway or my vehicle's brake lights, creating a high risk of rear-end collisions. Additionally, the rapid loss of coolant caused the engine to overheat and lose power while in motion, nearly causing a stall in active traffic. Confirmation: The failure was confirmed by the service department at Washington Hyundai (Invoice #174281). This is the second failure of this specific component (previously failed in Jan 2025). The manufacturer issued TSB 23-EM-009H for this defect, acknowledging it affects 2020-2023 Sonata Hybrids, but no safety recall has been issued. Symptoms: The issue was preceded by a "sweet" burning smell and a sudden "Engine Overheating" warning on the dashboard. The failed component has been replaced by the dealer, but the manufacturer refused to replace the coolant-poisoned Oxygen (O2) sensors, leaving the vehicle in a technically compromised state. The failed unit is likely held by the dealer for warranty parts return.

NHTSA ID

11727380

Incident

Feb 19, 2026

The EHRS coolant system failed and had a leak causing the coolant to be excessively burned off as thick white smoke. This caused me to not be able to see anything behind me and forced others to stop or slow down dramatically to avoid colliding with me. I had my engine overheat and force me to pull over on the side of an unsafe road because the exhaust system burned off my entire tank of coolant in less than a mile. I have taken this to a Hyundai dealership and they confirmed it was the EHRS system failure and told me it was a fairly known issue with the 2020-2023 Sonata Hybrids. I was told that even if I get it replaced the possibility of having it happen again are pretty high. This seems extremely unsafe to myself and others.

NHTSA ID

11719316

Incident

Feb 9, 2026

The vehicle's HVAC (heating) system failed. It stopped producing heat on one side of the vehicle. My mechanic/dealer diagnosed the issue as a broken component within the HVAC case under the dashboard, requiring full dashboard removal and a repair estimated at over $3,000. This failure prevents the defroster from working properly, which is a major safety hazard as it cannot clear fog or frost from the windshield. A search of online forums and owner communities shows this is a widespread complaint from many other Hyundai owners, often identified as a failed blend door or blend door actuator, which requires the same expensive dashboard removal to repair.

NHTSA ID

11698349

Incident

Sep 15, 2025

The contact owned a 2021 Hyundai Sonata. The contact stated that while driving approximately 70 MPH, the sunroof suddenly fractured. The contact stated that there was no external cause to the failure. The vehicle was taken to the dealer. The vehicle was not diagnosed nor repaired. The contact decided to trade the vehicle. The manufacturer was not made aware of the failure. The approximate failure mileage was 13,300.

NHTSA ID

11513262

Incident

Mar 20, 2023

Mileage

13,300 mi

My car barely has 11,000 miles and just the other day it had about 20miles left of gas but as I was driving on the road it started to feel and seem like it was about to die on me, Also the front Wipers are not well restrained with the vehicle you can tell by the way it moves when Wipers are on....Also most of the Signals be It if something is in front of me and the signal goes off BUT THERES NOTHING THERE ...ALSO WHEN IM BACKING UP SOMETIMES the car itself will Force stop as if something is in the way ...BUT AGAIN NOTHING IS THERE AT ALL ...IT HAPPENS EVERY FEW DAYS ....I JUST PURCHASED THIS CAR ..AND REALLY THINKING IT WAS WORST MISTAKE W ALL THESE ISSUES ALREADY

NHTSA ID

11509258

Incident

Feb 16, 2023

As I was driving down the road I heard what sounded like a gunshot and glass shattering. Upon getting to my destination I found that my panoramic sunroof had shattered outward.

NHTSA ID

11503651

Incident

Jan 25, 2023

*The front sunroof panel exploded toward while the car was running, but in the driveway in park. *Our safety was compromised by the shattered tempered glass falling into the car. *The problem was noted at the dealer, who stated they had not seen this happen before and believed it to be from a rock chip. *The roof has been inspected by the service department at the dealer, and pictures taken by them and by me. It has been reported to the manufacturer. *No problems noted prior to the “explosion”. Sitting in my car on a cold 27F morning, I started the car and turned on the front and rear defrosters and the heater. There was a light dusting of frost on the car. About a minute after I started the car, I heard a loud bang above me. When I opened the sunroof cover to see what the noise was, tempered glass shards fell in on me. When I got out of the car to see what had happened, the roof appeared to be exploded outward in circle about 10” across, although most of the sunroof glass was “crazed”. The car was not moving, had not had time to get warm, inside, there was no tree or other environmental hazard close to drop on the roof.

NHTSA ID

11499241

Incident

Dec 19, 2022

The contact owns a 2021 Hyundai Sonata. The contact received notification of NHTSA Campaign Number: 21V00M000 (Visibility) however, the part to do the recall repair was unavailable. The dealer was made aware of the issue and confirmed that parts were not yet available. The manufacturer was made aware of the issue. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The contact had not experienced a failure. VIN tool confirms parts not available.

NHTSA ID

11464009

Incident

Jan 1, 2022

Recall on my vehicle states there is still no remedy after one month.

NHTSA ID

11449486

Incident

Dec 27, 2021

The contact owns a 2021 Hyundai Sonata. The contact stated that while traveling at highway speeds, a tiny pebble hit his windshield which caused a minor ding on the middle of the driver’s side windshield. Over time, the ding spread from the driver’s side to the lane assist sensor located in the middle of the windshield. The contact stated that the crack spread vertically and horizontally across his windshield. He stated that the crack had obstructed his vision while driving at various speeds. The dealer was initially notified of the failure and informed him that he had to have the vehicle repaired by a recommended third party. The manufacturer had yet to be notified of the failure. The vehicle had yet to be repaired. The failure mileage was 23,000.

NHTSA ID

11445226

Incident

Nov 28, 2021

Mileage

23,000 mi

2021 Sonata N LINE NOT EQUIPPED WITH AUTO WIPERS WIPERS INTERMITTENTLY COME ON BY ITSELF WHILE DRIVING. IT HAS COME ON MULTIPLE TIMES WHEN USING MY TURN SIGNAL. WIPES ONCE THEN GOES OFF. HAS ALSO COME ON ONCE WITHOUT THE USE OF THE TURN SIGNAL. SWIPED 3 TO 4 TIMES AND THEN WENT OFF

NHTSA ID

11438621

Incident

Oct 15, 2021

PANORAMIC SUNROOF EXPLOSION. HAPPENED ON OPEN HIGHWAY ROAD WITH NO CAR IN NEAR VICINITY OR SIGN OF ANY KIND OF DEBRIS HITTING THE VEHICLE.

NHTSA ID

11405017

Incident

Mar 16, 2021

Mileage

5,836 mi