2021 Hyundai Elantra Hybrid problems

“Approximately once every 500 - 2000 miles (maybe more frequently this year), my car suddenly begins to accelerate hard. This happens even if my foot is completely off the gas pedal. Usually, before the problem becomes severe, there are a few minutes in which I suspect the car is sometimes lurching forward, or losing some ability to accelerate. Then the problem worsens til the car is almost undriveable... it speeds up, I slow it down with the brakes, I release the brakes, the car speeds up, I slow it down with the brakes again, and so on. The problem goes away right away when I turn the car off and then back on. I brought the car to the the dealer to investigate this when the car was still pretty new, but they found nothing. I did have a recall repair (software update) done that I thought was related to this, but it made no difference. The check engine light does not illuminate, and neither do any other warnings. It's very scary when it happens. When it's bad and I don't have an opportunity to pull off the road, I can shift to neutral and let the car coast to a stop at the side of the road. Or I can turn the engine off and then back on, while the car is still moving.”

“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.”

“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…”

“So the car will come to a dead stop. Then when I give gas, it will not go for 1-2 sec, then all of a sudden it go at high speed by itself. Even when I brake, it will feel like as if I have stepped onto gas. Very dangerous”

“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”

“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.”