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.
2021 Hyundai Sonata Hybrid engine complaints
Page 2 of 2: complaints 11 to 24 of 24, newest first, as owners wrote them.
Initially had loss of cabin heat. Later, vehicle randomly overheated. Repair shop replaced EGR due to finding confidant buildup of water/coolant mix. Within one week, problem returned. Dealer notified me that while replacing another part they found a TSB for coolant leakage into exhaust that was consistent with my issue. After research, it is clear that this is a widespread failure and should be a recall.
Hyundai 2021 Sonata Hybrid. Blown head gasket. Reported 1,000 miles after warranty expired. Car was in the shop for Hybrid battery issues. Repair completed. 2 weeks later smoke coming from the exhaust. Hyundai says blown head gasket - will not honor warranty as I was just a few thousand miles over warranty. Seems to be a common problem with the Hyundai not honoring the warranty.
Antifreeze is coming out of the exhaust. Heater is only blowing cold air. Repair shop said it is a common problem with the Hyundai hybrids. Was told I had to take it back to the dealership. The y repair shop said this is very common and is wondering why a recall has not been issued by the NTHSB. Dealership has been unresponsive.
My vehicle's heat stopped working suddenly. A short while later, I received and overheat warning for the engine. I had to stop repeatedly on the shoulder of the highway to allow the car to cool so I could move it to a safe space at the next exit. The dealer has confirmed that the coolant was leaking into the exhaust system and burning up. This resulted in white smoke, inconsistent power, and a stumbling engine when it would switch over from the electric to the gas engine. This problem comes on suddenly and can leave you in a very bad situation since there is no warning to this problem. The dealer reported my car had no coolant left in it which is why it was frequently overheating. I have read about this problem on many online forums and it seems to be very common in this car. Hyundai needs to create a fix.
While driving, engine alerted that it was overheating. Pulled over and coolant was very low, so I refilled it and then while driving to my family's garage to use the lift, saw white exhaust smoke. Took it to an independent mechanic, and in the ~10 mile trip there, over a quart of coolant had been burned off. He was able to reproduce the issue. No issues with the engine operation, it runs well and efficient, no check engine light. Mechanic found that a coolant line runs to the middle of the exhaust system and that this seems to be the issue. Other owners seem to have reported this same issue with this same model and roughly the same year, in which the muffler assembly needs replaced due to coolant leaking into the exhaust. Only prior issue was less warm air out of the vents for the previous week or so, but no other issues or warnings.
the coolant reservoir has been dropping showing levels below min even after topping it off
Discovered that I had no engine heat to use in the cabin with cooler outside temps. Checked coolant tank. Was nearly bone dry. 2021 hybrid is under warranty with only 35K miles on it and regular scheduled maintenance. Have also noticed puffs of white smoke upon easy acceleration and switching from battery to gas. Refilled engine coolant, but it continues to leak internally with use (no evidence of pooling under car) with short mile trips. Had to leave at dealership for repairs and cannot get a repair date for another month out. Other hybrid owners of 2020 and 2021 report their dealerships discovered the coolant is leaking into the engine and mixing with the exhaust (thus the white smoke). I am adding my car to the list of others who have reported the same problem.
This car is a Hybrid The car has a 12V battery reset system which stops the 12V battery from draining to zero voltage. This is a design feature. However, since purchasing this car we have had Hybrid Engine Failure warnings happen 3 times, in 2 months. When this happens the car engine shuts down, no matter at what speed you are driving! The car gives a warning on the dashboard that states - Hybrid System Failure - and the engine shuts down. The dashboard goes completely bland as all electronics are switched off. This has happened 3 times, 2 of them occurred on the freeway at high speed. Luckily we were able to pull over without being impacted by another vehicle. After a few seconds of stopping we are able to push the 12V Battery reset switch and the engine restarts when the start button is depressed. After the first incident the car was given to the local Hyundai dealer and they found nothing wrong with the car. It has happened twice since the car was returned to us and the car is currently in the Hyundai dealership, a different one, for diagnosis. We do not want to drive this car until the fault is determined and corrected
The contact owns a 2021 Hyundai Sonata. The contact stated that while driving at an undisclosed speed, he received an alert indicating that the engine was overheating and to pull over. No warning lights were illuminated. The contact then veered to the side of the road and waited approximately 15 minutes before restarting the vehicle. The vehicle was then taken to the dealer where the vehicle remained. The vehicle was diagnosed, and it was determined that the engine coolant bypass valve needed to be replaced. The vehicle had not yet been repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 32,547.
When I arrived in the parking lot and selected the R (reverse), the vehicle stayed in the D (Drive) although that it was moving backwards and was able to park it. The shift selector was stuck in DRIVE (Drive) leaving the vehicle on but not operational. After several attempts to allow the vehicle to cool and the battery to reset, (30 minutes_ later), the car started and took the vehicle to be serviced. The vehicle technician said they had a difficult time diagnosing the vehicle because it was giving different codes. They said that while testing they found the Transmission Shift Selector Module was damaged. Not physically but electronically damaged. They also stated that the car could have other problems but that they needed to replace the module first because it could be the cause of the other errors.
The cabin heater started blowing cold air in February. One shop said the car was low on coolant and topped it off. I made an appointment to take the car to a dealer because it's still under warranty (<37k miles). I had to wait 3 weeks. A few days before my appointment, the cabin heater started blowing cold air, again. There is no indicator that the coolant is low. The engine temperature is one of a dozen gauges one can scroll thru, but the "engine overheating" warning started flashing before I thought to check the temperature guage. Smoke came out of the exhaust and, once stopped, from under the hood. There was a risk of an engine fire and/or permanent damage to the engine.
Engine oil plug backed out while driving causing loss of all engine oil in the mountains. Drive time was one hour when oil lamp turned on as we reached our destination. Oil check stick had no oil on it and the whole undercarriage and rear of the car was covered in engine oil. Made an attempt to refill oil and plug fell all the way out and poured the new oil onto the ground. The oil plug is not visible or accessible due to a plastic cover on the underside of the car. The vehicle was towed to Elk Grove Hyundai dealership for service since they were the last hands on the car for regular maintenance. It was confirmed by the dealership the oil plug backed out on it's own. My family's safety was compromised as we were driving at night in steep mountains during high traffic time. There would be nowhere to go if the engine ceased and would cause an accident on HWY 50 in California. Also a full six quarts of oil was leaking on the back roads, highway, and residential roads, and eventually in a high school parking lot was were the bulk of the oil was spilled. The is an environmental hazard at public school Eldorado High School.
Very loud car alarms sounded, e.g., it sounded like a something like a red alert in an old Star Trek episode. warning light indicated engine overheated, extreme exhaust/smoke bellowed out from rear of car while decelerating on highway exit ramp. My wife and I were inside the car during this event. This event happened on 5 pm EST December 9 at Hamilton Avenue exit on Ohio 126 Cross County Highway (Ronald Reagan Highway) in the Cincinnati metropolitan area. Had to park car within one mile. I had the car towed to the nearest dealer after it had cooled for 1 +hour. I was afraid the engine was going to explode or catch fire as I was decelerating. The dealer suggests the heat exchanger needed replacement. However, after 45 days, Hyundai has not shipped the heat exchanger that I have been made aware. I am concerned this event may be likely to reoccur and with resulting potential injuries to the occupants inside.
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