2021 Toyota Highlander

Vehicle starts to produce humming and whining sounds as speed picks up from underneath the vehicle, likely from the transmission/final drive gear area. This problem is consistent and persistent. The whining noise stops when the throttle is released and will resume as throttle is engaged. More reported cases of transmission failure, sudden lost of propulsion and grinding noise are found on public forums. Toyota issued a service bulletin about this problem. Toyota issued extended warranty to prior model years from 2016 to 2017 of the same issue. This will affects millions of Toyota sold with the UA80, UA80E and UA80F transmissions in the US.

whine when accelerating. toyota has released a tsb 0008-21 indicating to replace transmission due to incorrect installation of a retaining clip on a nut securing differential in place. Nut can Become loose and stuck in gears of internals of transmission causing transmission to lock up while driving. this will cause loss of power and could result in an accident. Toyota is aware of the issue but refuses to make repairs due to vehicle being outside of powertrain warranty. Toyota has extended warranty to 10 years on 2017 and 208 model years however the problem still exist in 2017-2024 model years with the same transmission UA80E/UA80F

When our vehicle reached about 70,500 miles (10,000 miles past when the powertrain warranty expired), the vehicle started making high-pitched whining noises when the gas pedal was depressed. We brought it to the Toyota dealership and were advised that the vehicle's transmission needed to be replaced and were quoted $9,700. This is for a vehicle that was only 4 years old!! We do not feel that this is a repair/issue that a consumer must bear the cost of! When we shared this with the Toyota technician, he stated that unfortunately, the Highlander's powertrain warranty expired at 60,000 miles. We understand that Toyota was aware of this issue and this should have been escalated as a NHTSA recall where the manufacturer should be responsible for the cost of repair and/or replacement, not the consumer. Please assist us with obtaining a satisfactory resolution with this.

I purchased a 2021 Toyota Highlander in June of 2024 with about 45k miles. The transmission completely failed at 67k miles, when I brought it in to have checked in April of 2024. This is not covered under warranty and is costing 7-8k in repairs and over 3k in rental vehicles. I'm told the transmissions are on back order for 3-6 months. No lights went off in the car warning me of this. I smelled burning fumes on and off and reported it to the service dept around 59k (January 2024) miles. I did feel a jump at times, but didn't report that. After my routine oil change at the end of March of 2025, I heard a whining noise only when accelerating and would immediately stop when I released my foot. Two Toyota Service departments diagnosed my car with a failed transmission. I haven't been able to drive my car for 2 months now. My family's safety has been at risk while this issue with this transmission failure has been known and not reported to the consumers prior to my purchase in June of 2024. Potential consequences to a failed transmission while driving are as follows: -Sudden Stop or Coast to a Stop: The car might stop moving entirely, especially if internal components seize or it just loses power and I coast to a stop. -No Response to Acceleration -Pressing the gas has no effect, which is dangerous if I'd be in traffic or on a highway. -Locked-Up Transmission -Rare but possible, especially in catastrophic mechanical failure which could cause wheels to lock briefly. -Stranded

[XXX] [XXX] [XXX] [XXX] [XXX] Vin # [XXX] 2021 Toyota Highlander 4DR AWD XLE I am writing to report a potentially dangerous transmission defect in my 2021 Toyota Highlander XLE, at approx. 60-70k miles. The vehicle recently developed a high-pitched whining noise while accelerating, which a certified Toyota service technician suspects is internal to the transmission. This exact issue is outlined in Toyota Technical Service Bulletin T-SB-0008-21, issued February 9, 2021, for 2021 Highlanders equipped with the UA80E or UA80F 8-speed automatic transmission. According to the TSB, the cause is worn pinion shafts in the front carrier assembly, and the prescribed repair is complete transmission replacement. Unfortunately, my vehicle was just outside the 60,000-mile powertrain warranty window, despite experiencing the failure consistent with a known manufacturer defect. Numerous other owners have reported identical symptoms between 60,000–80,000 miles, often facing repair costs over $8,000 and multi-week delays due to part availability. This is not a typical wear-and-tear issue. A failure of the transmission at highway speeds or during critical maneuvers could lead to loss of power or control, posing a real safety risk to drivers and passengers. I respectfully urge the NHTSA to investigate this issue further. I am happy to provide: Thank you for your commitment to driver safety. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

There is a known defect with transmissions in certain model years of Toyota cars, mine being one of them, per this TSB: [XXX] The transmission can catastrophically fail but Toyota will not replace the defective part unless the vehicle is still under warranty. I had the Toyota dealer verify that the transmission is beginning to fail and requires replacement. The transmission has begun to emit a "whining" noise. Should the transmission fail catastrophically during operation, it could cause a sudden loss of power, seize a drive wheel, or another event causing a loss of vehicle control. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)