2021 Toyota Highlander: complete transmission failure

Filed Nov 6, 2026 · Transmission · IA

There is Powertrain - Transmission failure on my 2021 Highlander V6 8 speed with just over 50,000 miles. Toyota is aware of transmission failures with the Highlander family of vehicles equipped with the UA80 transmission. The failure with the UA80 transmission can cause a sudden power loss in traffic which escalates it to a safety issue. My Vehicle has been inspected by the Toyota dealership and confirmed to be well-maintained. Transmission failure confirmed by dealership and documents have been shared with Toyota Corporate (Toyota Motor North America). Toyota is refusing to take any responsibility, cover any cost associated, or do any recall, putting their consumers and others at risk.

Filed Nov 5, 2026 · Transmission · TN

The transmission started whistling around 66k miles. It was diagnosed by 3 different dealerships, including Toyota, as a transmission failure. It was diagnosed as a known issue with this year Highlander, with no fix on the market. I am having to pay $10k out of pocket because this is out of warranty by 6k miles. Highly dissappointed.

Filed Nov 4, 2026 · Transmission · MI

**Component:** The 8-speed automatic transmission (Aisin UA80F, AWD) failed internally. A Toyota dealer test-drove the vehicle on 10/09/2026 and verified the noise comes from transmission internals. The repair order states: "Internal transmission failure causing whining noise while driving/accelerating." **Safety risk:** The transmission is failing internally and has not yet failed completely; if it does while driving, it could cause a sudden loss of motive power. I am reporting it because the same failure mode is documented in Toyota service bulletin T-SB-0008-21 (front carrier assembly pinion shafts), but this transaxle — serial A4A20M 00395, built at TMMWV in December 2020 — is immediately outside the bulletin's affected range (A4A20L00101–A4A20L01824, November 2020). It failed identically, which suggests the November 2020 production change did not fully correct the defect. **Inspection:** A Toyota dealer confirmed the failure by test drive and inspection. Toyota (the manufacturer) has not inspected the vehicle. No police or insurance inspection. **Symptoms:** A whine at all speeds. No warning lamps or messages. No crash, injury, or fire.

Filed Oct 29, 2026 · Transmission · PA

My 2021 Toyota Highlander XLE began making a high-pitched whining noise when accelerating. When researching this noise, associated with the make, model, and year of my vehicle, it became apparent that the noise is associated with a manufacturer's defect in the [XXX]‑speed transmission (Toyota [XXX]). The cited notification states that the correction for this defect is a transmission replacement that is only covered by the 60,000 mile/5 Year warranty. There are three class-action lawsuits associated with this issue, and I wanted to document my incident in the event that my service appointment with [XXX] Toyota in [XXX], on 11/23/2026 indicates that my transmission is affected by the defect so many have experienced. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Oct 9, 2026 · Transmission · 70,100 miles · PA

The contact owns a 2021 Toyota Highlander. The contact stated that while driving at an undisclosed speed, there was a loud high-pitched whining sound coming from the vehicle. The contact stated that the vehicle hesitated while accelerating and the transmission was shifting rough. The contact stated that the vehicle had experienced an internal transmission failure. The manufacturer was notified of the failure. A local dealer was contacted and associated the failure with Toyota Technical Service Bulletin: 0008-21. The contact stated that a diagnostic test was scheduled. The failure mileage was 70,100.

Filed Oct 4, 2026 · Transmission · NE

65K miles on the vehicle and have started to get a whining noise from the transmission during acceleration. UA80F transmission installed with multiple class action lawsuits against Toyota for this issue as it leads to catastrophic failure with high replacement cost. Stopped driving the vehicle and looking into transmission replacement options. Toyota needs to be held liable for mechanical defects.

Filed Sep 30, 2026 · Engine · KY

I own a 2021 Toyota Highlander Platinum AWD equipped with the 3\.5L V6 and approximately 77,000 miles\. The vehicle developed a humming/whining, airplane\-like noise from the front drivetrain while accelerating\. The noise increases with vehicle speed and stops when the accelerator is released\. There is no vibration, and the vehicle makes the same noise while traveling straight\. I took the vehicle to an authorized Toyota dealer, Kerry Toyota, and the dealer diagnosed the transmission as the source of the noise and recommended replacement of the transmission\. The quoted replacement cost is approximately $7,600 plus tax\. Toyota previously issued Technical Service Bulletin T\-SB\-0008\-21 concerning a whine or grind from certain 2021 Highlander UA80 transmissions and identifying the front carrier assembly pinion shafts as a potential cause\. My vehicle is approximately 17,000 miles beyond Toyota’s 60,000\-mile powertrain warranty\. I contacted Toyota requesting goodwill assistance with the transmission replacement, and Toyota declined assistance\. I believe there may be many similar cases involving 2021 Toyota Highlanders equipped with the UA80 transmission, including vehicles experiencing comparable whining or grinding noises and premature transmission\-related failures\. I am reporting this because an internal transmission problem that develops shortly beyond the powertrain warranty may worsen and could potentially result in loss of vehicle propulsion\. I believe the federal safety agency should review this issue along with similar complaints involving 2021 Toyota Highlanders equipped with the UA80 transmission\.

Filed Sep 14, 2026 · Transmission · WI

Transmission Failure Yes TSB No Warning Lights

Filed Sep 14, 2026 · Transmission · IN

Tech: SCOTT RICHART test drove vehicle performed inspection. Noise hear is coming from transmission internally. condition present is similar to condition described in T-SB-0008-21 for whine noise from transmission. Transmission would need replaced to remedy the noise. Vehicle is out of warranty, DOFU is 04/14/21. Transmission is not in the serial number range described in the TSB. Transmission serial # is A3A21C08858. QUOTED $8574.50 TO REPLACE TRANSMISSION WITH REMANUFACTURED TOYOTA TRANSMISSION.

Filed Sep 14, 2026 · Transmission · 58,000 miles · IN

The contact owns a 2021 Toyota Highlander. The contact stated that while driving 22 MPH, there was an abnormal sound coming from the vehicle. The dealer was contacted by phone and made aware of the failure. The vehicle was taken to the dealer, where it was diagnosed with transmission failure. The contact was informed that the transmission needed to be replaced. The manufacturer was contacted by phone, and a case was filed. The contact was informed that the repair was not covered under recall. The failure mileage was approximately 58,000.

Filed Sep 10, 2026 · Transmission · WI

Leadcar Toyota LaCrosse WI has diagnosed and reported that the transmission needs to be replaced. Pertains to Service Bulletin T-SB-0008-21 the pinion shaft bearing defect. The major powertrain component is failing prematurely. Cost to repair is over $9,000 as it is out of warranty. We purchased the vehicle at 67,550 miles on 3/29/2025. Since we never owned a Toyota before we thought the whining of the transmission was unique to that vehicle. Once we heard about the service bulletin we took it in to get diagnosed.

Filed Sep 9, 2026 · Transmission · IN

transmission has failed. Toyota states: Toyota Technical Service Bulletin T-SB-0008-21 addresses a whining or grinding noise in select 2021 Toyota vehicles equipped with UA80E orUA80F automatic transmissions caused by a defect in the front carrier assembly pinion shafts. Yes it can be available for inspection. This can be repaired with a $12,000 new transmission. * Sudden loss of acceleration: You may press the gas and the vehicle doesn’t accelerate normally. This is particularly dangerous when merging onto a highway, crossing an intersection, or passing. How this toyota highlander is putting safety at risk: * Unexpected shifting or jerking: A failing transmission can slam into gear, hesitate, or shift unpredictably, potentially causing loss of control. * Loss of drive: The transmission may suddenly stop transferring power to the wheels. You could be unable to move forward even though the engine is running. * Getting stuck in a gear: If it goes into a “limp” or failsafe mode, the vehicle may be restricted to a single gear and have very limited acceleration. * Loss of power while already moving: If the transmission disengages unexpectedly, you can lose the ability to accelerate out of a dangerous situation. * Difficulty maintaining speed: On a highway or uphill, a failing transmission may suddenly stop providing adequate power. * Transmission fluid leaks: A significant leak can cause the transmission to lose lubrication and worsen rapidly. Depending on where fluid goes, it can also create other mechanical problems. * Unexpected engine RPM increases: The engine can rev very high without the Highlander gaining speed (“slipping”), which can leave you unexpectedly slow in traffic. * Being stranded in traffic: A complete failure can leave the vehicle immobile, creating a collision hazard if you’re stopped in a travel lane or on a shoulder. unknown if it has been inspected by anyone. There is no warning lights. Then only way you know is by a high whining sound.