2018 Hyundai Tucson electrical system problems

“Issues: 1. Stop lights failure light turns on and off. 2. Engine light failure notification turns on and off. 3. Headlights low bims failure notification turns on and off. Actions taken: 1. Headlights low bims bulbs were changed. 2. Engine light codes reviewed and updated as report showed; however, warning light still turning on. 3. Stop light fuse has been changed, light bulbs still working.”

“While driving to work, the vehicle abruptly shut down in the middle of the highway. There were no signs or warning given. The vehicle was towed almost 100 miles home. The vehicle was later jump started and the alternator and battery were tested and it passed all tests.”

“While driving my 2018 Hyundai Tucson Limited 1.6L Turbo with the 7-speed EcoShift dual clutch transmission (DCT), the vehicle has repeatedly failed to engage and hold gears, resulting in loss of motive power in traffic. Diagnostic scanning retrieved codes P074B (Unable to Engage Gear 3), P074B71 (Unable to Select 3rd Gear), P074B07 (Gear Dropped Out of 3rd Gear), P092177 (1st Gear System Referencing Failure), and P0921 (Gear Shift Forward Actuator Circuit Range/Performance). A Hyundai dealer diagnosed the failure as requiring transmission replacement at approximately 93,000 miles. This is the same 7-speed DCT and the same failure mode addressed by NHTSA Campaign 16V628000 (Hyundai Recall 149) and Hyundai Service Campaign T1B, which covered 2016–2017 Tucson vehicles but excluded the 2018 model year despite using the same transmission. Hyundai has acknowledged this defect in 2018 vehicles through TSB 21-AT-014H and TSB 22-AT-007H, which prescribe a TCU software update, but issued these as service bulletins rather than a recall, so owners were never notified. When I requested the TSB software update, the Hyundai dealer refused to perform it. This defect creates a…”

“While idling at a standstill (in a drive-thru queue), my 2018 Hyundai Tucson suddenly experienced a severe engine overheat, causing the vehicle's air conditioning system to immediately blow hot air and shut down. The vehicle was brought directly to an authorized Hyundai dealership (Chapman Hyundai on [XXX]) for an emergency inspection.The dealership's certified technicians confirmed that the electric Engine Cooling Fan Assembly completely failed and subsequently caused the main Front Wiring Harness and Fuse Box to physically melt. The dealership documented this catastrophic electrical and thermal meltdown under Repair Order #XXX.This is a critical safety defect. A melted engine wiring harness poses an immediate and severe risk of an electrical short circuit, sudden vehicle stalling in live traffic, or a catastrophic under-hood engine fire. Because this component controls the primary cooling of the powertrain, its failure creates an extreme hazard to the vehicle occupants and surrounding traffic. Hyundai must investigate this component failure before it results in a thermal fire incident or an accident due to sudden power loss.”

“While driving on a public road, the vehicle experienced multiple simultaneous, dangerous malfunctions: Dashboard Warnings: All lights illuminated, including engine (flashing), ABS, traction control, airbag, TPMS, and parking brake, which stayed on though disengaged. Engine & Transmission: Tachometer fluctuated wildly in park; engine revved without accelerator input. Shifting to drive/reverse caused unexpected “kicks.” Vehicle sometimes failed to move when pressing gas, requiring engine restart. Driving Issues: Speedometer read 0 or jumped inconsistently. RPM continued erratically while maintaining speed without accelerator. Steering became extremely difficult. I immediately determined the vehicle was unsafe to drive and returned home with it, which was only a couple miles away. Follow-Up: Hyundai advised dealership diagnosis; they suggested a backup camera module will resolve the issues I experienced in entirety, but also in the same email stated that they could not guarantee it would resolve all of the issues I experienced. This is the second major engine/powertrain failure: first approximately ~70,000 miles (full engine replacement), current approximately…”

“My 2018 Hyundai Tucson experienced complete engine failure at around 118,000 miles. The motor suddenly blew without warning. This vehicle uses an engine type known for widespread engine defects, including bearing wear and internal failure. I bought the vehicle used in 2023, maintained it regularly, and there were no warning lights or overheating before the failure. I had to put oil in my vehicle every week. I had to use 5qts of oil. It smelled like fumes coming through the vents. It then stalled on the highway while we had our son in the vehicle and shaked profusely. Mind you we had our son in the vehicle. How unsafe is that. I then did my research and found out Hyundai engines of this generation have a history of stalling, seizing, and internal damage. I am filing this complaint because this appears to be part of a known safety defect that can cause sudden loss of power while driving. We took it to shop and confirmed the motor blew. It was faulty. Also, sometimes the electrical components would turn off in vehicle such as radio and would go black. Also the turn signal would be on and then turn off. It would also shake while driving. This needs to be taken care…”