Hyundai Sonata battery drain problems

Filed Sep 3, 2026 · Electrical, Transmission · TX

I am submitting a safety complaint regarding a recurring, unresolved electrical defect in my 2020 Hyundai Sonata SEL. The vehicle fails to recognize when the ignition is switched off, leaving core vehicle systems active and causing severe parasitic battery drain that leaves the car immobilized. ​Description of the Problem: ​False "On" Status: After parking, turning off the engine, and exiting the vehicle, the car continues to register as though the ignition is still active/on (accessories, cluster, or vehicle network remain awake). ​ Severe Parasitic Draw: Because the vehicle fails to shut down its electrical circuits, the 12-volt battery repeatedly discharges overnight or while parked for short durations. ​Battery Replacement Did Not Resolve Issue: The 12-volt battery was replaced with a brand-new unit to eliminate typical wear, yet the drain and false "on" behavior persisted immediately. ​ Frequency: The vehicle frequently fails to start, requiring constant jump-starts or roadside assistance to operate. ​Safety Hazard: This defect creates a direct safety risk by repeatedly stranding the driver without warning in public locations, traffic stops, or remote areas. In addition, an electrical system that fails to enter a sleep state creates a potential hazard for component overheating, failure of electronic security and locking systems, or total electrical failure while attempting to restart or operate auxiliary safety equipment. Other Hyundai owners have reported identical issues where the body control modules or ignition logic fail to power down. ​Corrective Action Requested: I request that the federal safety agency investigate this electrical shutdown defect across the 2020 Hyundai Sonata model year to identify whether a faulty Body Control Module (BCM), smart key receiver, or ignition switch relay requires a safety recall and software or hardware remediation. Battery replaced on 09/04/2026 Car inspected/diagnosed by Hyundai Dealership on 09/03/2026

Filed Dec 6, 2025 · Engine · MD

New Battery keeps dying, car not starting and when it does start it shuts off when I brake. Oil light on after I already put oil in the car

Filed Nov 17, 2025 · Electrical, Engine · OH

The vehicle experienced an engine and power train failure while driving on the highway, resulting in sudden loss of power. The electrical system also failed after the dealer visit, causing the battery to die every morning. Yes, the vehicle is available for inspection upon request. My car suddenly lost power on the highway and would not accelerate, forcing me to pull over on the shoulder with traffic moving around me. This created a serious risk of a rear-end collision or crash. Additionally, after the dealer visit, the electrical system began failing and the vehicle has been completely dead every morning, leaving me stranded with a child and unable to reliably start the car. The problem has not been reproduced because the check engine code cleared itself after the incident; however, the symptoms absolutely remain. The dealer refused to diagnose the loss-of-power event because the code was cleared, and they returned the vehicle to me with a dead battery. The electrical issue (car dying every morning) has been happening consistently since the dealer visit. The vehicle was taken to a Hyundai dealership immediately after the incident, but they refused to diagnose the loss of power due to the code being cleared. A mobile mechanic scanned the code at my home before the tow, but the code disappeared afterward. The electrical failure began after the dealer visit and has not been properly inspected by Hyundai. Yes. While driving on the highway, the check engine light came on and the car immediately lost power and would not accelerate. After the dealer visit, the car has been completely dead every morning and requires a jump to start. These symptoms began on the same day as the highway incident and continued after Hyundai serviced the vehicle.

Filed Oct 9, 2025 · Lights · TX

My car has a problem whith the break lamps, the sockets that hold the bulbs are melting and they have deformed making it hard to replace the fused bulbs. Also the brake light stay on even after the engine is off draining the Battery and causing a short circuit.

Filed Sep 20, 2025 · Engine · CA

I bought this vehicle on [xxx],I didnt recieve any information about recalls,I was driving on [xxx] at 60 MPH and noticed the dash lights came on, somehow I was able to coast far enough and merge 2 lanes and was sitting between the offramp and the freeway ,the seemed like a dead battery or wouldnt turn over, soon a california state tow truck pulled up he tried to jump it ,nothing, he towed me to a safe place, then I called triple a same thing, I was towed home after I assumr the crankshaft cooled it started with a knock, there was no knock when it siezed, I got home and seen they gave me gwc warranty, im paying for they didnt even mention that when I bought it, ,the story is worse this was the second car from this dealer,the first one I had 1 day and heard rods knocking on cold starts I took it right back, thats how they got me in this I was kinda cornered, I called gwc they said send it to a dealer so I sent it to hyundai ,at first they told me the engine siezed and said its covered by hyundai, then said the next day they denied it becouse the knock sensor update was never completed from 2020,I only had the car 1 month it siezed on [xxx],so now there trying my gwc coverage who tells hyundai they will cover a used engine,I said ok, I have been communicating with the hyundai service manager, he did tell me over the phone he doesnt believe it was even legal for them to sell me that car,also yes the blinkers did constantly go the wrong way,I didnt know about that recall either I know it was upsetting me,every time I look my blinker was going the other way,,I see lots of recalls and problems with the hyundai engines,how do I realy know if that was or wasnt taken care of for this car or was there a knock sensor recall in 2020, the car has 144,000 miles I bought it with 141,051, hyundai warranty becouse engine siezure is 150,000, its still sitting at hyundai waiting for gwc to say go ahead ,he keeps telling me they will let me know tomarow,I have no car, information redacted pursuant to the freedom of information act

Filed Jul 8, 2025 · Brakes, Electrical · IL

I drive a 2012 Hyundai Sonata Limited. After a recent fill-up, I began experiencing delayed acceleration, engine hesitation, and what appears to be misfiring—especially at low throttle. Most notably, the brake lights stay illuminated even when the car is turned off, which drains the battery and poses a major safety hazard. I scanned the vehicle with an OBD-II scanner and received code P0504, which points to a brake light switch malfunction. I also noticed that pressing the start button with my foot off the brake still starts the engine instead of going into accessory mode—confirming abnormal brake signal behavior. I replaced the brake light switch, which temporarily fixed the issue, but the symptoms returned within a day. After researching, I found there was a recall (the federal safety agency 15V759000) for a nearly identical issue involving the brake light switch and stopper pad. However, my VIN is not listed, even though I am experiencing the same safety-critical symptoms. This issue poses a significant safety risk on the road, and I believe my vehicle should be included in the affected population of the recall or issued a Technical Service Bulletin extension.

Filed Jul 27, 2023 · Brakes, Electrical · 18,178 miles · MO

The contact owns a 2013 Hyundai Sonata. The contact became aware that the brake lights were illuminated without the brake pedal being depressed. The contact restarted the vehicle and the failure persisted. The contact stated that due to the brake lights remaining illuminated, the battery terminal had to be disconnected to avoid draining the battery. The contact stated that after one failure, a mechanic pulled over to the side of the roadway and the contact was informed that a sensor related to the brake lights had failed and needed to be replaced. There were no warning lights illuminated. The vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The approximate failure mileage was 18,178.

Filed Mar 10, 2023 · Electrical · FL

Similar to other complaints here and in other forums: Faulty lights: flickering off and on while driving at night, unable to use the lights in “auto” mode or else they flicker/battery drains and flickering with use of turn signals. Has been reoccurring since at least 2021 and has worsened over time

Filed Feb 2, 2023 · Lights · 180,000 miles · WA

The contact owns a 2012 Hyundai Sonata. The contact stated upon starting the vehicle, the brake light was illuminated. Additionally, the contact stated that the failure had been draining the battery. The contact stated that the battery, the alternator, and the starter were replaced with the assistance of a friend. The dealer and the manufacturer were not notified of the failure. The vehicle was not diagnosed or repaired. The contact related the failure to an unknown recall. The failure mileage was approximately 180,000.

Filed Nov 26, 2022 · Electrical · MN

Since November 2021, my 2013 Hyundai Sonata is found to have a dead battery on multiple random occasions. I replaced the battery with a brand new battery twice before bringing it in for inspection at a Hyundai dealer on September 1, 2022. The dealer diagnosed the problem as an electrical short circuit within the rear view mirror console and replaced said part for $711. The vehicle has had a dead battery twice since that repair, indicating there is still an electrical draw/short circuit somewhere within the vehicle. Each instance of a dead battery was preceded by rainy humid weather. I brought the vehicle back to the Hyundai dealer on November 14, 2022. I explained that I suspected moisture was getting in somewhere that it shouldn’t be and causing the electrical short circuit thus draining the battery. The Hyundai dealer found no electrical short and documented that the electrical system was performing to specifications (no electrical draw found that exceeds 50MA). There have been no dashboard warning lights or messages indicating the issue. Hyundai has no solution. I have replaced the battery three times within one year. I am concerned that the undiagnosed electrical problem may lead to a fire while parked and off and/or a dangerous failure while driving. Vehicle is available for further inspection upon request.