2021 Hyundai Elantra Hybrid problems

ELECTRICAL SYSTEM:PROPULSION SYSTEM:HYBRID MANAGEMENT

The contact owns a 2021 Hyundai Elantra Hybrid. The contact stated that while driving 60 MPH during ice and snow, the engine revved, and there was an abnormal sound coming from the Hybrid battery. While turning, the contact stated that the vehicle had unintendedly accelerated. Additionally, the tire pressure warning light was illuminated. The contact believed that the failure was related to the Hybrid battery. The vehicle was driven to the residence, where it remained parked and was not driven since. The manufacturer was notified of the failure. The failure mileage was 44,900.

NHTSA complaint #11708400 — an unverified report by a vehicle owner.

EXTERIOR LIGHTING

The headlights and back lights turn off at random times when the headlights are on the automatic setting. This problem happens very frequently at night, putting my family at risk when the lights go off and cannot see what is ahead of us. In addition to a cop pulling me over for not having my lights on and he asked me if I was playing with the lights since they were going on and off and luckily the cop did not give me a ticket when I explained and he saw the problem (he advised me to get on this website and to make a report). I have reported this problem to the Hyundai dealership for the past 3 years and I don’t even think they take the time to investigate. The dealership just keeps telling me that with another update in the software is going to get fixed. But that is not the case. This is a very dangerous problem that is going to get someone killed. Need to be fixed

NHTSA complaint #11672296 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

The headlights and back lights turn off at random times when the headlights are on the automatic setting. This problem happens very frequently at night, putting my family at risk when the lights go off and cannot see what is ahead of us. In addition to a cop pulling me over for not having my lights on and he asked me if I was playing with the lights since they were going on and off and luckily the cop did not give me a ticket when I explained and he saw the problem (he advised me to get on this website and to make a report). I have reported this problem to the Hyundai dealership for the past 3 years and I don’t even think they take the time to investigate. The dealership just keeps telling me that with another update in the software is going to get fixed. But that is not the case. This is a very dangerous problem that is going to get someone killed. Need to be fixed

NHTSA complaint #11672296 — an unverified report by a vehicle owner.

POWER TRAIN

Check Hybrid System alarmed in heavy traffic and derated my car and put me in a very dangerous situation.

NHTSA complaint #11671060 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

I am writing to report a serious and ongoing safety issue with my 2021 Hyundai Elantra Hybrid that remains unresolved despite multiple visits to Hyundai service centers and independent repair shops. I’ve also found numerous consumer discussions online describing nearly identical issues with the same model and newer Elantra Hybrid models, suggesting this may be part of a wider systemic defect. The core issue lies within the vehicle’s hybrid system. Shortly after a recent system/software update performed at a Hyundai dealership, a warning message began appearing at random intervals stating: “Check Hybrid System.” This typically first appears after extended driving — often around 3 hours — but once it occurs, the issue worsens if I continue to drive. Each time the warning appears, the vehicle suddenly and drastically decelerates without driver input, becoming dangerously slow and unresponsive, even while traveling at highway speeds. This creates an urgent safety risk, as I have had to maneuver off the road quickly to avoid collisions. After the initial warning, if I attempt to drive the vehicle again without sufficient downtime, the warning reappears much more frequently — sometimes within minutes. The only temporary relief is to stop using the vehicle and allow it to rest for at least six hours, after which the issue may temporarily subside. In every case, I must use the 12V battery reset button to restart the car, which I suspect may be clearing diagnostic codes before they can be properly recorded. Notably, the check engine light disappears after this reset, even if it was previously displayed. Given that the hybrid battery is located beneath the rear passenger seat, I am deeply concerned that if there is an underlying thermal or electrical issue, it could pose a serious or life-threatening risk to passengers. To date, no dealership or technician has been able to duplicate or permanently resolve the problem.

NHTSA complaint #11661670 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

I am writing to report a serious and ongoing safety issue with my 2021 Hyundai Elantra Hybrid that remains unresolved despite multiple visits to Hyundai service centers and independent repair shops. I’ve also found numerous consumer discussions online describing nearly identical issues with the same model and newer Elantra Hybrid models, suggesting this may be part of a wider systemic defect. The core issue lies within the vehicle’s hybrid system. Shortly after a recent system/software update performed at a Hyundai dealership, a warning message began appearing at random intervals stating: “Check Hybrid System.” This typically first appears after extended driving — often around 3 hours — but once it occurs, the issue worsens if I continue to drive. Each time the warning appears, the vehicle suddenly and drastically decelerates without driver input, becoming dangerously slow and unresponsive, even while traveling at highway speeds. This creates an urgent safety risk, as I have had to maneuver off the road quickly to avoid collisions. After the initial warning, if I attempt to drive the vehicle again without sufficient downtime, the warning reappears much more frequently — sometimes within minutes. The only temporary relief is to stop using the vehicle and allow it to rest for at least six hours, after which the issue may temporarily subside. In every case, I must use the 12V battery reset button to restart the car, which I suspect may be clearing diagnostic codes before they can be properly recorded. Notably, the check engine light disappears after this reset, even if it was previously displayed. Given that the hybrid battery is located beneath the rear passenger seat, I am deeply concerned that if there is an underlying thermal or electrical issue, it could pose a serious or life-threatening risk to passengers. To date, no dealership or technician has been able to duplicate or permanently resolve the problem.

NHTSA complaint #11661670 — an unverified report by a vehicle owner.

ENGINE

I am writing to report a serious and ongoing safety issue with my 2021 Hyundai Elantra Hybrid that remains unresolved despite multiple visits to Hyundai service centers and independent repair shops. I’ve also found numerous consumer discussions online describing nearly identical issues with the same model and newer Elantra Hybrid models, suggesting this may be part of a wider systemic defect. The core issue lies within the vehicle’s hybrid system. Shortly after a recent system/software update performed at a Hyundai dealership, a warning message began appearing at random intervals stating: “Check Hybrid System.” This typically first appears after extended driving — often around 3 hours — but once it occurs, the issue worsens if I continue to drive. Each time the warning appears, the vehicle suddenly and drastically decelerates without driver input, becoming dangerously slow and unresponsive, even while traveling at highway speeds. This creates an urgent safety risk, as I have had to maneuver off the road quickly to avoid collisions. After the initial warning, if I attempt to drive the vehicle again without sufficient downtime, the warning reappears much more frequently — sometimes within minutes. The only temporary relief is to stop using the vehicle and allow it to rest for at least six hours, after which the issue may temporarily subside. In every case, I must use the 12V battery reset button to restart the car, which I suspect may be clearing diagnostic codes before they can be properly recorded. Notably, the check engine light disappears after this reset, even if it was previously displayed. Given that the hybrid battery is located beneath the rear passenger seat, I am deeply concerned that if there is an underlying thermal or electrical issue, it could pose a serious or life-threatening risk to passengers. To date, no dealership or technician has been able to duplicate or permanently resolve the problem.

NHTSA complaint #11661670 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

I have a safety recall is with a Rear view camera that hasn’t had a solution.

NHTSA complaint #11632655 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

The Hybrid charging system fails once the vehicle is above 75 mph. After about an hour or two, the vehicle will die on the highway. This is a reoccurring issue putting our safety at risk. The dealership cannot find what the problem is. Online forums show similar issues with dealerships unable to solve the problem.

NHTSA complaint #11624498 — an unverified report by a vehicle owner.

SUSPENSION

At around 93k miles my HECU unit apparently malfunctioned at the same time as the left front tire speed indicator. All of my safety features ABS, adaptive cruise control, lane departure, lane keeping etc do not work because of this.

NHTSA complaint #11621727 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

At around 93k miles my HECU unit apparently malfunctioned at the same time as the left front tire speed indicator. All of my safety features ABS, adaptive cruise control, lane departure, lane keeping etc do not work because of this.

NHTSA complaint #11621727 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: WARNINGS

At around 93k miles my HECU unit apparently malfunctioned at the same time as the left front tire speed indicator. All of my safety features ABS, adaptive cruise control, lane departure, lane keeping etc do not work because of this.

NHTSA complaint #11621727 — an unverified report by a vehicle owner.

ENGINE

The contact owns a 2021 Hyundai Elantra HEV. The contact stated while driving 65 MPH, the vehicle started to lose motive power with a battery warning light illuminated. The contact stated that on several occasions, the vehicle had to be turned off and restarted for the vehicle to recharge and restart. The vehicle was taken to the dealer, but the vehicle was not diagnosed or repaired. The contact informed the dealer that the failure was intermittent and within an hour the dealer stated had replicated the failure. The manufacturer was notified of the failure. The failure mileage was approximately 52,000.

NHTSA complaint #11592150 — an unverified report by a vehicle owner.

VEHICLE SPEED CONTROL

When gas is pressed (even to floor) in drive, vehicle stalls, does not accelerate. Then vehicle jerks into propulsion after revving. Other instances, at deceleration the car will jerk and shake to a stop. I have mentioned the problem at every scheduled maintenance

NHTSA complaint #11586175 — an unverified report by a vehicle owner.

FUEL/PROPULSION SYSTEM

When gas is pressed (even to floor) in drive, vehicle stalls, does not accelerate. Then vehicle jerks into propulsion after revving. Other instances, at deceleration the car will jerk and shake to a stop. I have mentioned the problem at every scheduled maintenance

NHTSA complaint #11586175 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

I was driving on the Highway at the posted speed limit when the warning "Check Forward Safety System" came up and remained on my dashboard. The cruise control stopped working also. The light remained on even after stopping and starting the car and has remained on ever since. I have never been in an accident nor has my computer system reported any collision. My Hyundai Blue Link app gives me the following DTC: C162078. It started on [XXX]. My collision detection system does not appear to be working at all and my cruise control no longer works. I'm very concerned about it malfunctioning based on other entries on the nhtsa.gov website. I took the car to Hyundai Service Center and they are trying to convince me this is due to a collision and warranty will not be covering it. They tried to charge me for diagnostic even though I already had the error code on the Hyundai BlueLink App. They confirmed that my computer has zero reports of any collisions. The service tech said, and I'm quoting, "The system is very sensitive and a swift kick could cause it to malfunction." That sounds like a manufacturing defect to me. I have never been in an accident with this car, there is zero visible damage to the front bumper, and my computer has no report of an accident. The dealership urged me to contact insurance. My Major Insurance Company told me this was absurd, would never be approved, and is clearly mechanical. They also mentioned anecdotally that this problem has been coming up a lot for them with modern Hyundai models. Then I called Hyundai Corporate and they have escalated the issue, agree it sounds mechanical, and will be contacting me in 3-5 business days. They apologized profusely so I am still holding out hope for warranty coverage. I believe the dealership is trying to blame me for this mechanical failure to avoid expense on their end. I have had many software-related issues with this car. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11572957 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: WARNINGS

I was driving on the Highway at the posted speed limit when the warning "Check Forward Safety System" came up and remained on my dashboard. The cruise control stopped working also. The light remained on even after stopping and starting the car and has remained on ever since. I have never been in an accident nor has my computer system reported any collision. My Hyundai Blue Link app gives me the following DTC: C162078. It started on [XXX]. My collision detection system does not appear to be working at all and my cruise control no longer works. I'm very concerned about it malfunctioning based on other entries on the nhtsa.gov website. I took the car to Hyundai Service Center and they are trying to convince me this is due to a collision and warranty will not be covering it. They tried to charge me for diagnostic even though I already had the error code on the Hyundai BlueLink App. They confirmed that my computer has zero reports of any collisions. The service tech said, and I'm quoting, "The system is very sensitive and a swift kick could cause it to malfunction." That sounds like a manufacturing defect to me. I have never been in an accident with this car, there is zero visible damage to the front bumper, and my computer has no report of an accident. The dealership urged me to contact insurance. My Major Insurance Company told me this was absurd, would never be approved, and is clearly mechanical. They also mentioned anecdotally that this problem has been coming up a lot for them with modern Hyundai models. Then I called Hyundai Corporate and they have escalated the issue, agree it sounds mechanical, and will be contacting me in 3-5 business days. They apologized profusely so I am still holding out hope for warranty coverage. I believe the dealership is trying to blame me for this mechanical failure to avoid expense on their end. I have had many software-related issues with this car. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11572957 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL

I was driving on the Highway at the posted speed limit when the warning "Check Forward Safety System" came up and remained on my dashboard. The cruise control stopped working also. The light remained on even after stopping and starting the car and has remained on ever since. I have never been in an accident nor has my computer system reported any collision. My Hyundai Blue Link app gives me the following DTC: C162078. It started on [XXX]. My collision detection system does not appear to be working at all and my cruise control no longer works. I'm very concerned about it malfunctioning based on other entries on the nhtsa.gov website. I took the car to Hyundai Service Center and they are trying to convince me this is due to a collision and warranty will not be covering it. They tried to charge me for diagnostic even though I already had the error code on the Hyundai BlueLink App. They confirmed that my computer has zero reports of any collisions. The service tech said, and I'm quoting, "The system is very sensitive and a swift kick could cause it to malfunction." That sounds like a manufacturing defect to me. I have never been in an accident with this car, there is zero visible damage to the front bumper, and my computer has no report of an accident. The dealership urged me to contact insurance. My Major Insurance Company told me this was absurd, would never be approved, and is clearly mechanical. They also mentioned anecdotally that this problem has been coming up a lot for them with modern Hyundai models. Then I called Hyundai Corporate and they have escalated the issue, agree it sounds mechanical, and will be contacting me in 3-5 business days. They apologized profusely so I am still holding out hope for warranty coverage. I believe the dealership is trying to blame me for this mechanical failure to avoid expense on their end. I have had many software-related issues with this car. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11572957 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

I keep getting intermittent HEV warnings and 12-volt light. The engine then shuts down and I have no power. This has occurred several times while on the highway and this creates a safety hazard. I have been fortunate enough that this happened while I was close to the shoulder, otherwise, it could have been critical. - The failed component(s) are the 12 volt battery and engine shutdown - With the vehicle being without power while on the highway puts other drivers and myself at risk of an accident - I have taken the vehicle to two different Hyundai dealers and they have not resolved the problem - The issue was escalated to the manufacturer Hyundai Motors and they have not resolved this issue. - The 12v battery light and an HEV warning light comes on and then the engine shuts off - This issue has been happening intermittently for the past year and I first notice it on October of 2022

NHTSA complaint #11554043 — an unverified report by a vehicle owner.

FUEL/PROPULSION SYSTEM

I keep getting intermittent HEV warnings and 12-volt light. The engine then shuts down and I have no power. This has occurred several times while on the highway and this creates a safety hazard. I have been fortunate enough that this happened while I was close to the shoulder, otherwise, it could have been critical. - The failed component(s) are the 12 volt battery and engine shutdown - With the vehicle being without power while on the highway puts other drivers and myself at risk of an accident - I have taken the vehicle to two different Hyundai dealers and they have not resolved the problem - The issue was escalated to the manufacturer Hyundai Motors and they have not resolved this issue. - The 12v battery light and an HEV warning light comes on and then the engine shuts off - This issue has been happening intermittently for the past year and I first notice it on October of 2022

NHTSA complaint #11554043 — an unverified report by a vehicle owner.

ENGINE

This is my second time contact and reporting this issue about the vehicle surging unexpectedly and you cannot get it to slow down except by keeping your foot on the brake and pulling off the road. This has happened multiple times since I have had this vehicle. Recently, I had the car in for service and they said they did a recall for the software to stop this condition from happening again. However, 1 month later, it happened and this time it was the worst I have ever experienced as I kept my foot off the accelerator - it surged over 15mph from the speed I was originally at with me doing nothing and it was still gaining. My car was trying to accelerate with my foot on the brake and I had to cross lanes of traffic to get to the side of the road to restart the vehicle. The reason that it was the worst, is that I literally could not begin to control this vehicle. Other times it has happened and I could at least go for a little bit as long as I kept my distance from other cars but this acceleration was beyond out of control. I could have caused an accident or hit somebody. No warnings appeared, no messages or lights.

NHTSA complaint #11551172 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

My 2021 Hyunadai Elantra HEV Blue 12v battery light comes on and I lose power to the engine and all internal electrical components. It has happened while driving on the highway and it is a safety concern. I have addressed it with the dealership and they stated there were no codes and they canot replicate.

NHTSA complaint #11541657 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

the h e v warning light comes on when driving. the hybrid battery disconnects from the engine and the car is undriveable. have to pull over, stop the car, turn off the car and then reset the hybrid battery. this has happened twice in last week. thank fully i was able to pull over safely, but this a dangerous situation for me and other cars around me. the car had been taken to the dealership just two weeks ago and they were unable to diagnose the issue

NHTSA complaint #11528504 — an unverified report by a vehicle owner.

ENGINE

the h e v warning light comes on when driving. the hybrid battery disconnects from the engine and the car is undriveable. have to pull over, stop the car, turn off the car and then reset the hybrid battery. this has happened twice in last week. thank fully i was able to pull over safely, but this a dangerous situation for me and other cars around me. the car had been taken to the dealership just two weeks ago and they were unable to diagnose the issue

NHTSA complaint #11528504 — an unverified report by a vehicle owner.

FUEL/PROPULSION SYSTEM

the h e v warning light comes on when driving. the hybrid battery disconnects from the engine and the car is undriveable. have to pull over, stop the car, turn off the car and then reset the hybrid battery. this has happened twice in last week. thank fully i was able to pull over safely, but this a dangerous situation for me and other cars around me. the car had been taken to the dealership just two weeks ago and they were unable to diagnose the issue

NHTSA complaint #11528504 — an unverified report by a vehicle owner.