2018 HYUNDAI SONATA Power Train Problems

While driving on the highway, my 2018 Hyundai Sonata experienced sudden loss of engine power and became undrivable. The failure occurred without warning at approximately 86,500 miles. At the time of the incident, there were two children in the vehicle, and the breakdown occurred at night in cold temperatures (approximately 20°F). An authorized Hyundai dealership later diagnosed zero compression in cylinder 3 and confirmed a cracked piston, recommending full engine replacement. The sudden loss of power while driving created a safety risk due to traffic conditions and environmental exposure.

During multiple dealership visits in 2025, my 2018 Hyundai Sonata Limited 2.0T was repeatedly returned in unsafe condition. Southern Hyundai installed both front CV axles and torqued them incorrectly. The right axle was later confirmed under-torqued by about 50 ft-lbs, and the left axle was later found over-torqued 40ft-lbs Priority Hyundai later identified and corrected the under-torqued right axle, which briefly improved symptoms but did not resolve the underlying issue. When I returned for a follow-up on October 29, 2025, for a documentation-only appointment due to an active corporate case, the dealer ignored my instructions and altered evidence by loosening and re-torquing the left axle nut without consent. They recorded the torque at 250 ft-lbs in the repair order but failed to capture the required photos or before/after readings and referenced the wrong vehicle’s torque specification (Hyundai Elantra) in the documentation. Since then, the vehicle has continued to show steering pull, vibration, and instability at speed. Several visits showed only 0–3 miles of verification driving after safety-critical repairs involving brakes, suspension, and driveline components. Aftermarket parts were installed when OEM parts were promised, and uneven tire wear developed quickly. Safety risks include wheel-bearing damage, steering loss, and driveline separation due to repeated improper torque and altered evidence. Independent Firestone and Honda technicians have verified these issues. The matter remains under active Hyundai Corporate Case #[XXX]. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Engine failure. Definitely a safety issue, check engine light flashing, limited engine power. Wouldn’t accelerate. Dealer inspected, there is a nationwide recall and class action lawsuits and they won’t replace even though it’s under warranty. False information saying maintenance neglect on my part. That is FALSE. Known failure and oil consumption. Rod bearing failure.

The contact owned a 2018 Hyundai Sonata. The contact stated that while driving at an undisclosed speed, the vehicle sputtered, jerked, and lost motive power. The check engine warning light was illuminated. The vehicle was able to restart but made an abnormal ticking sound. The vehicle was taken to the dealer but was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 72,000.

Mileage: 72,000

The engine shuts off, doesn’t start, check engine light flashing, losses power, jerks while driving it, i will get it up yo speed then will shut off or won’t move.

The car in recent months has twice lost power and been rendered in operable on the side of the road until it could be limped home. I had the car serviced last year for a recall of a fuel filter gasket and at that time I was informed that I also had an update done for a (k knock?) sensor prior done on the car before purchase. I inquired about what that was, and they told me at the time it was for an engine recall because that particular engine I have is known to have rod bearing failure and consume oil without any trace of where it goes and piston rattle. I told the gentleman after my fuel gasket was taken care of that I would like to look into that because I have the symptoms and would like to know. At that point in time, I was told that I may have to do an oil test to see if the car loses oil. I said well can we do that and he told me it's $300 out of pocket. I asked on average before anything ever done by Hyundai, how many times do people have to do this? He said 4 to 6 in his experience. I told him I did not have the money, but I will keep an eye on the car. Everything's been fine for six months a few months ago Randomly driving to work the car shut down on me. We got the car home and my fiancé did an oil change and new spark plugs and the car worked fine. June 9th 2025 on my way to work the issue happened again in the middle of traffic. I called my fiancé and we got the car home. He performed another oil change and spark plug replacement and took pictures this time because the spark plugs are gunked up. The car now runs again. He called Hyundai of America on my behalf to just ask them if they could set up the test to see if the car was failing and they told him that they were all independent Hyundai and he would have to pay the test fees. He told them in a formal email that he doesn't believe under the federal recall He is responsible for that and they answered back that he may be reimbursed. We are contacting you because we were advised to on the issue

The engine stalls when driving, loses power, hard time to start. It uses an extensive amount of oil. Losing power/stalling can result in accident or fire in my engine. Yes check engine light came on said it was coils/plugs changed them 2xs already. Took it to a mechanic was told there’s a recall on engine it’s a valve that is not getting air through that can potentially case a Fire in my engine.

The car went into limp mode they have problems with the knock sensor and that is what it threw to the computer and I changed the sensor and went away and now limp mode again and computer says basically the same thing there is a software update and the engines are failing

My 2018 Hyundai Sonata (approx. 60,000 miles) began consuming excessive oil, and the engine started smoking while driving. My wife barely made it to the dealership — the car was unsafe, struggled to stay running, and visibly smoked from under the hood. Hyundai acknowledged the oil issue but refused to cover engine replacement. Instead, they approved a one-time combustion chamber cleaning and requested we drive the car 1,000 miles to "see if it gets better." This is a major safety concern. The vehicle is part of a group of Hyundai models known to have defective Theta II engines that have led to engine failure, fire risk, and recalls. This issue is widespread, and Hyundai is not taking proper responsibility for defective engines in cars like mine.

I was going 80 mph on the interstate and suddenly my car went into limp mode and shooked really hard and dropped to 60 mph. I had to swerve to go onto the side of the road. The car behind me almost rammed into me. I contacted hampton hyundai for days to schedule an appt. I finally was able to drop off my vehicle to them but now they are telling me they have to do an oil consumption test but my car is in limp mode and it shakes when I drive it. The car is dangerous and they are trying to charge me $500 for a fuel pump replacement ( which I have a warranty of but they notified me that does not count but it matches exactly the possible reason). As you can see in the documents, they did not note that my fuel pump was broken. They just asked if I wanted to pay it so they can get started. I get normal oil changes done. They haven't even done a rod bearing test but just looked at the knock sensor and was telling me that they wanted to charge me to get that changed.

When my car suddenly stopped on the highway, I encountered an issue with the “body control module.” The car wouldn’t start, and the key fob was ineffective. Additionally, the airbags stopped working. I don’t recall all the details, but I was unsure of where to report the dangerous vehicle. I’ve noticed several other Hyundai owners complaining about this issue, where their cars suddenly stop in the middle of nowhere.

My car is part of a campaign due to rod-bearing failure where the engine experiences problems such as complete failure, vibrating, hesitating, engine light on, and oil light on. I've been communicating with Hyundai who is not helping me with this issue. I was advised by them to continue driving the car "until the engine seizes", or I hear "a loud knocking noise". Upon inspection, three local Hyundai employees "agreed 100%" I need a new engine. However, per these employees Hyundai Corporate will not approve the replacement even though the vehicle is constantly experiencing the above symptoms above, simply because there is not a "loud knocking noise" coming from the engine. Even though ALL the other issues are present. This is very unsafe. I have a minor child I take to school daily, for an advisor to advise to drive the vehicle until "the engine seizes" is extremely dangerous, especially when they are aware my VIN is associated with engine replacement. My car exhibits symptoms of a rod-bearing failure and this multi-billion dollar company is taking advantage of hard-working urban mothers, by turning a blind eye and trying to require me to pay thousands of dollars up front for a problem THEY created by selling a vehicle with faulty engine. Again, the technicians indicated i in fact do need the engine replaced, but that Hyundai Corporate will require me to pay for a diagnostic test, rod-bearing test, and engine compression test because Corporate does not take their word for it. The fact a auto manufacturer is advising people to drive in such an unsafe manner is disheartening. If my child and I get injured in an accident by following their advice, our blood will be on their hands!

Severe oil leak into the oil pan has required frequent maintenance to keep oil in the car.

On [XXX] I was driving on [XXX] [XXX] from Rockville, Maryland when my vehicle (2018 Hyundai Sonata Limited) started to lose power and control and all dash lights started to show. I was able to move the vehicle to the highway shoulder before all power and control failed. Had I been moving at a higher speed or in heavier traffic, or been slower to react this could have led to a catastrophic incident. When the roadside assistance showed up they found that my alternator had completely detached from my vehicle. The vehicle was towed to the Sheehy Hyundai dealership in Waldorf, MD and examined on [XXX]. The maintenance staff informed me that there were 3 other similar cases they're working on, and that there is a flaw in the design of the alternator bracket using aluminum materials that failed, and that they've reported this systemic issue to the manufacturer but have yet to receive any indications that this would be considered for a recall despite the catastrophic impact this could have. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Starter replaced at less than 50,000 miles. Normally a starter will last 150,000 miles or more. I was past the warranty by 9 months but was under the mileage. Warranty was 5 years or 50,000 miles. Hyundai parts are cheap and do not last long compared to other companies.

I have had a new engine put in my Sonata back at the beginning of 2023. For the past two days my car will jerk really hard, and then loose power not accelerating over 25 rpms and my check engine lights comes on when it jerks really hard.

The contact owns a 2018 Hyundai Sonata. The contact stated while driving 70 MPH, the vehicle went into LIMP Mode and lost motive power. The contact was able to pull to the side of the roadway, where the vehicle failed to restart. The check engine warning light was illuminated. The vehicle was towed to an independent mechanic, who determined that cylinder #1 was misfiring on every cycle due to damage to the piston. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 107,000.

Mileage: 107,000

My car is misfiring, hesitating accelerating, severely shaking and vibrating which you can feel in the pedals and steering wheel, and the check engine light is on. This issue has been ongoing for over a week already. When the engine light first came on on 9/7, i pulled over on the side of the road and had a mobile mechanic check it out. The code was coming up as a bad ignition coil in cylinder 1. When he took out the coil and spark plugs, he saw scoring on the spark plug from oil as well as oil being consumed in the cylinder itself which has been causing my vehicle to misfire. The mobile mechanic stated on his invoice that I need a new engine. I took my car to Faulkner Hyundai on 9/11 and they said the best they can do is an oil consumption test even though they personally know I need an engine as well. I have not been able to drive the vehicle due to the ongoing issues, I am afraid for my life and safety that god forbid the car stalls out on the highway while I am traveling to or from work I could get into a major accident. They are putting my life in jeopardy.

The contact owns a 2018 Hyundai Sonata. The contact stated that while driving approximately 60 MPH the vehicle suddenly began sputtering and then completely stalled. The contact had to coast to the side of the road and noticed the check engine light illuminated. After approximately 10 minutes, the vehicle was able to restart. When starting the vehicle there would be a sputtering followed by the vehicle shutting off. The failure began to occur while idle as well. The contact stated that while attempting to reverse out of a parking spot the vehicle suddenly accelerated forward instead. As a result, the vehicle ended up crashing into a concrete light post. The air bags did not deploy. There were no injuries or medical attention needed. The vehicle was able to be driven after. No police report was filed. The vehicle had been towed to the dealer who had stated that the starter relay issue may be the cause, however, because of not being able to duplicate the failure they were unable to give an official diagnosis. The vehicle had not been repaired. The manufacturer was not made aware of the failure. The approximate failure mileage was 86,000.

Mileage: 86,000

transmition problem , stop and go high rev engine sutck in geer angine stals in stop and go tslow moving trafic

The contact owns a 2018 Hyundai Sonata. The contact stated while driving 70 mph, he heard an abnormal noise, and the vehicle began to vibrate. The contact stated no warning light was illuminated. The contact was able to park the vehicle at a nearby parking lot. The vehicle was not drivable. The contact towed the vehicle to the local dealer. The vehicle was not diagnosed or repaired. The manufacturer had been informed of the failure. The failure mileage was approximately 50,000.

Mileage: 50,000

My 2018 Hyundai Sonata GDI Engine stop working while I was driving on the freeway without a warning prior to the issue. It never gave me a heads up in advance that the engine needed service. No check engine light to alert me that an issue needed attention. I learned about the engine problem when my engine stop working while I was on the freeway. I heard a loud noise coming from the engine and within seconds my RPM started going down and my car started loosing power while I was driving on the freeway. At the same time my check engine light came on and it was flashing. At that moment I realize something bad was happening with my motor. The check engine light was not on before that. It never alerted me before that, and when it came on flashing on and off it was already too late because my engine was dying and it died and didn't turn back on after I pulled over in the side of the freeway. I was so scared. The cars where going so fast and very close to my car with little room to pull over. The high velocity of the others cars where making my car cradle from the wind. It was so terrifying for me and my little dog i had with me. My seat belt stop working a few weeks before my engine died, and the thought of me getting hit by another car without a seat belt on. I've never been scared for my life like I was on that day. Hyundai dealer sold me a car with a bad engine. I was putting atleast 1 quart of oil every other week sometimes every week in the past year until just recently. I've only had it for 3 years since I bought it and I was putting 1 quart of oil every month in the beginning and with time the consumption of oil increased and increased more with time. Hyundai service my car for an oil gasket last year that should've been cover under warranty, but made me pay for it. I made it aware to them about the excessive oil consumption and told them it wasn't normal how much oil the car was consuming but they denied to service my car under warranty.

I was stopped at a red light and when it turned green, I began to accelerate. The car stuttered and the check engine light was blinking. I pulled over and had Autozone run the code. The code is P1326, engine knock sensor. It was put into limp mode and it shook pretty bad in lower gears while accelerating. I had to pull over and let several cars pass me as I couldn't go above 2,000 RPMs. When I got home, I called roadside assistance and had it towed to the nearest dealership. That was this morning (5-4-2022). I just purchased this car used in the beginning of March. I don't have all the records since I just purchased the vehicle used. I just changed the oil last week.

WHEN ACCELERATING FROM A STOPPED POSITION THE VEHICLE SHUDDERS OR STUTTERS BEFORE PROPER ACCELERATION IS ACHIEVED. I OWNED A FORD FIESTA THAT DID THE SAME THING AND IT TURNED OUT TO BE THE CLUTCH. IS THAT A POSSIBILITY WITH MY SONATA?

Mileage: 28,000

IN FEB 2020 MY SONATA WENT INTO SAFE MODE AFTER EXITING HIGHWAY AND DEALER ENDED UP REPLACING "KNOCK SENSOR". IN DECEMBER 2020 MY ENGINE "STUTTERED" THROWING ME FORWARD AS IF I HAD HIT BRAKES HARD. NO WARNING LIGHTS OR MESSAGES OCCURRED AND AFTER A FEW SECONDS CAR ACTED NORMALLY MOSTLY. A FEW DAYS LATER AFTER EXITING HIGHWAY AGAIN THE ENGINE WARNING LIGHT (ORANGE) CAME ON ALONG WITH ERROR MESSAGE "POSSIBLE CONDITION WITH ENGINE CONTROL SYSTEM" HAS BEEN DETECTED. CAR DID NOT GO INTO "SAFE MODE" AND SEEMED TO BE OPERATING NORMALLY. I CONTACTED DEALER WHO ASSURED ME SAFE TO DRIVE OVER HUNDRED MILES BACK TO DEALERSHIP IN THIS CONDITION TO CHECK. I DROVE BACK FROM EAST COAST FL TO WEST COAST FL TO TURN CAR IN. I BELIEVE ENGINE ISSUE EXPERIENCED IS RELATED TO THE THETA ENGINE ISSUE AND REPAIR WOULD BE COVERED UNDER SETTLEMENT. DEALERSHIP DISAGREES AND HAS INDICATED ISSUE IS WITH FUEL PUMPS (BOTH ARE BEING REPLACED) AND CHARGING ME $2300.

Mileage: 147,000

I GET A HEV WARNING TELLING ME TO SHUTDOWN MY CAR. WHEN THIS HAPPENS MY VEHIVAL NO LONGER ENGAGES THE GAS PART OF MY MOTOR, THE CAR GIVES ME MULTIPLE DISTRACTING NOISES. AFTER TURNING THE CAR OFF AND BACK ON IMMEDIATELY THE GASOLINE SIDE OF MY MOTOR IS WORKING AGAIN.. P2600 POPS UP ON MY SCANNER AND THE CHECK ENGINE LIGHT REMAINS ON TILL ABOUT 4 IGNITION CYCLES WITH SOME DRIVE TIME. ALMOST ONCE, AND SOMETIMES TWICE A DAY FOR THE PAST THREE DAYS THIS HAS BEEN AN ISSUE.

Mileage: 33,500

I WAS DRIVING MY CAR AT ABOUT 45MPH ON MY WAY TO WORK ON A HIGHWAY ROAD AND OUT OF NO WHERE IT JERKED AND THE CHECK ENGINE LIGHT STARTED FLASHING. CAR WOULD NOT ACCELERATE ABOVE 2,000 RPMS. WHEN THE CAR JERKED, IT WAS SO SUDDEN IT INJURED MY LOWER BACK. MY BACK HAS BEEN VERY SORE SINCE THIS INCIDENT. I THEN TOOK TO DEALER AND THEY SAID IT WAS A KNOWN ISSUE AND HYUNDAI HAD NOT RECALLED MY SPECIFIC CAR. DEALER WAS ABLE TO REPLICATE THE ISSUE. THE CLEARED THE CHECK ENGINE LIGHT AND SENT ME ON MY WAY. ONE MILE DOWN THE ROAD EXACT SAME THING HAPPENED. CAR IS CURRENTLY AT THEIR SHOP WITH NO ETA OF REPAIR.

I WENT INTO PURCHASING DEALER FOR FIRST OIL CHANGE AT 5100 MILES, THEY FLASHED COMPUTER AND LOADED UPDATE HYUNDAI CAMPAIGN 953 PRODUCT IMPROVEMENT. ABOUT 50 MILES AFTER THE RECALL WAS PERFORMED MY CAR WENT INTO LIMP MODE AND IS BARELY DRIVEABLE. CAR WAS ALSO HESITATING, AND BUCKING A BIT. TOOK IT BACK TO DEALER THEY STATED THE CODE DIDN'T APPLY TO MY CAR AND FLASHED IT AGAIN. IT AGAIN WENT INTO LIMP MODE AFTER 50 MILES OR SO. THE RECALL IS SUPPOSED TO PLACE THE VEHICLE IN LIMP MODE DUE TO ROD BEARING WEAR. MY CAR HAS 5,400 MILES ON IT AND IT NOW AT A DIFFERENT DEALER. GOT INFORMATION FROM THAT DEALER REGARDING A TBS #19-01-002 AND LOOKS LIKE ENGINE REPLACEMENT OR WIRING HARNESS.

Mileage: 5,400

I HAD A RECALL PERFORMED ON MY CAR. 'HYUNDAI CAMPAIGN 953 PRODUCT IMPROVEMENT '. 10 MILES AFTER THE RECALL WAS PERFORMED MY CAR WENT INTO LIMP MODE AND IS BARELY DRIVEABLE. THE RECALL IS SUPPOSED TO PLACE THE VEHICLE IN LIMP MODE DUE TO ROD BEARING WEAR. MY CAR HAS 5,560MILES ON IT AND THE ENGINE IS ALREADY FAILING.

Mileage: 5,560

PURCHASED NEW 2018 SONATA SEL MODEL IN CALIFORNIA. WHILE DRIVING, THE TRANSMISSION STARTS TO HARD DOWNSHIFT WHEN THE BRAKE IS APPLIED. I FOUND OUT THAT THIS HARD DOWNSHIFTING AND JOLTING/THUMPING OF ENGINE AND TRANSMISSION ONLY OCCURS WHEN COMING TO A STOP AT SPEEDS BETWEEN 10 TO 15MPH. IT CAN BE DESCRIBED AS FOLLOWS, AFTER THE BRAKE PEDAL HAS BEEN GENTLY APPLIED AND LIGHTLY RELEASED BUT THEN THE CAR ITSELF APPLIED ITS BRAKE AGAIN. IT TERRIFIES THE DRIVER'S DRIVING CONDITIONS, MENTALLY AND PHYSICALLY.

Mileage: 1,100

THROTTLE RESPONSE: FEELS LIKE THE OLD VEHICLES WITH A FLAT SPOT IN THE CARBURETOR ACCELERATOR PUMP. THE "THREE SECOND' RULE APPLIES WHEN THE THROTTLE PETAL IS PUSHED. THERE IS A SERIOUS HESITATION AS THE ENGINE TENDS TO FALL FLAT BEFORE ACCELERATING. HAS TO DUE WITH THE SIX SPEED AUTOMATIC TRANSMISSIONS DUEL CLUTCH WHICH ACTS AS IF A PERSON WERE OPERATING A STANDARD TRANSMISSION CLUTCH. I HAVE DISCUSSED THIS PROBLEM/CONCERN SEVERAL TIMES WITH THE SERVICE DEPARTMENT WHERE THE VEHICLE WAS PURCHASED. THE SERVICE DEPARTMENT INDICATED THEY RECEIVE NUMEROUS COMPLAINTS. IT IS INDICATED THE DRIVERS EITHER LOVE THE VEHICLE WITH THIS PROBLEM OR HATE. WE WERE NEVER TOLD OF THIS SITUATION. AND THERE IS NO FIX FOR THIS. THIS SITUATION CAN OCCUR WHEN LEAVING A STOPPED POSITION, WHEN TURNING RIGHT OR LEFT FROM A STOPPED POSITION, ACCELERATING UP A HILL IN MOVING TRAFFIC OR ON A STREET. THIS ALL DEPENDS ON THE DRIVERS REACTION TO THE THROTTLE PEDAL. WHEN ONE NEEDS TO ACCELERATE WHILE IN MOTION THERE TENDS TO BE A SHUDDERING/STUTTERING OF THE ENGINE. THIS PROBLEM HAS OCCURRED SHORTLY WE PURCHASED THE VEHICLE IN FEBRUARY 2018 AND HAS BEEN ON GOING. I SET THE "WHEN DID THIS HAPPEN" AS STARTING DATE. CAN BE VARY CONCERNING WHEN ENTERING TRAFFIC FOR OLDER DRIVERS. I CANNOT FIND ANY MORE DESCRIPTIONS FOR THIS SITUATION. THERE ARE NO DOCUMENTS AT MY DISPOSAL AT THIS TIME. THANK YOU.

Mileage: 40