2021 Toyota Highlander Engine Problems

I own a 2021 Toyota Highlander with approximately 127k miles. The vehicle has developed a noticeable whining/whirring noise during acceleration. The noise appears to originate from the drivetrain/transmission area and has become increasingly noticeable over time. The condition occurs every-time during acceleration and is present under normal driving conditions. I am concerned that this may indicate a transmission or drivetrain-related issue that could affect vehicle reliability and safety. I have found reports from other 2021 Toyota Highlander owners describing similar symptoms involving whining noises during acceleration. The vehicle has been inspected by a Toyota dealership. And is certified through Toyota. The vehicles was bought new from the Toyota dealership and has had all service done through Toyota. I am submitting this complaint so NHTSA can evaluate whether this condition is part of a broader pattern affecting similar vehicles as a defect in the original transmission built in the SUV.

NHTSA ID

11745579

Incident

Jun 11, 2026

Transmission leak requiring torque converter replacement

NHTSA ID

11742152

Incident

May 5, 2026

My vehicle was parked for about an hr 30 min , and it started smoking from dashboard area and immediately went into flames .

NHTSA ID

11735002

Incident

Apr 28, 2026

Car makes a high pitched whining noise at low speeds of approx. 10-30 mph

NHTSA ID

11733929

Incident

Apr 26, 2026

Transmission has failed as have many others of the same year make and model without acknowledgement of a manufacturer defect

NHTSA ID

11731278

Incident

Apr 3, 2026

The vehicle experienced a transmission failure at approximately 62,000 miles, which required a transmission replacement. Toyota replaced the transmission with a rebuilt transmission. Immediately after the repair, the vehicle began experiencing multiple issues that were not present prior to the repair. The vehicle initially would not reverse, and the battery was drained shortly after the repair was completed. Following the repair, the vehicle has continued to experience ongoing electrical malfunctions, including dashboard warning lights, system alerts, and dash lights flashing during remote start. The vehicle has also developed a rattling noise underneath the vehicle. The exact failed component has not been clearly identified. The dealership has provided changing diagnoses and has not provided written diagnostic documentation despite requests. The vehicle has been inspected by the dealership multiple times; however, the issues have not been resolved. During a recent diagnostic, the dealership stated that the catalytic converter is now the issue, but this does not address the ongoing electrical problems. These issues raise safety concerns due to unpredictable vehicle behavior and potential failure of critical systems while driving. Warning lights and system errors began appearing after the transmission repair and have continued since that time. The vehicle is available for inspection upon request.

NHTSA ID

11730329

Incident

Feb 11, 2026

When accelerating at all, the engine emits a whining noise. The only time the whine stops is when the foot is removed from the pedal. It does not whine at idle. I believe it is the transmission going bad. The problem has been confirmed by a local service center. No warning lamps or messages have appeared.

NHTSA ID

11729882

Incident

Feb 16, 2026

The contact owns a 2021 Toyota Highlander. The contact stated that while driving at an undisclosed speed, there was a whining sound coming from the vehicle. There was no warning light illuminated. The vehicle was taken to the dealer, where it was diagnosed with transmission failure. The dealer stated that the transmission needed to be replaced. The vehicle was repaired. After the vehicle was parked and turned off, there was transmission fluid leaking from the vehicle. There was no warning light illuminated. The vehicle was taken back to the dealer, where it was diagnosed and determined that the head gasket had failed and needed to be replaced. The vehicle was repaired. The contact then noticed fluid leaking from the transfer case while the vehicle was parked and turned off. The vehicle was taken back to the dealer, where it was diagnosed and determined that the transfer case had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure. The approximate failure mileage was 74,700.

NHTSA ID

11721799

Incident

Mar 3, 2026

Mileage

74,700 mi

Complete transmission replacement for failure. Toyota said it is an unknown issue but has not issued a recall for 2020/2021 models. THIS NEEDS TO BE A RECALL. Toyota should be responsible, especially because they will not cover it if you go over your manufacturer warranty of 60k. I purchased this car last week, and had to get a full new transmission the following week because they did not disclose to me that it was failing!

NHTSA ID

11716104

Incident

Feb 2, 2026

Vehicle makes a loud noise when under 65mph. Car shakes when breaking. Transmission needs to be replaced.

NHTSA ID

11716074

Incident

Feb 4, 2025

whinning noise during acceleration on the road and gear shift problems

NHTSA ID

11714697

Incident

Jan 28, 2026

- The vehicle has been experiencing shifting issues (its an automatic vehicle) when driving in all instances and at all speeds that has progressively gotten worse over the past 4-8 weeks. - As it seems to be a transmission issue (and a known one pending litigation) the safety issue is if the transmission fails during operation of the car. - It was brought to a dealership to be inspected after it was initially felt as more of a vibration than the more harsh shifting/engine sounds and issues that it is currently experiencing. The dealership thought it to be the front hub assembly/bearing that was the issue. I had the front driver side replaced and the issue still remains and has continued to worsen. It has not been inspected by the manufacturer, police, or insurance representative. - There have been no warning lamps or messages at all. - Through research it appears this is a known issue with ongoing litigation (2 class action lawsuits currently in litigation related to UA80F transmissions of which it appears that our VIN is in the affected group).

NHTSA ID

11713495

Incident

Jan 26, 2026

We have been hearing whining coming from the front of the vehicle for months. Over the life of our time with this car, we have reported to Toyota multiple times about the sound, and about how sometimes the engine seems slow to shift. The whining increases as you press the gas pedal. Toyota is aware of this issue with Highlanders, but has told us they aren't going to fix it, as there is no recall on the issue. Turns out, there's a TSB related to the exact issue that we have with our Highlander. Now that we are out of warranty, we are looking at potentially replacing the transmission of a vehicle that Toyota has a record of intentionally avoiding to repair. Multiple independent service centers have confirmed the issue. They all have referred us back to Toyota because of the severity of the issue. There were no warning lamps or lights or the issue. However, the "whining" is audible every time in the vehicle.

NHTSA ID

11713066

Incident

Jan 1, 2025

My transmission is making acceleration unreliable, whining noise and unreliable. No accident yet but I took to toyota and they quoted $8K for entire new transmission when it appears this is a known ongoing issue for toyota highlanders. They should be recalled and fixed.

NHTSA ID

11709492

Incident

Dec 12, 2025

I have a faulty transmission that is now widely known. 2021 Highlander with the UA80 transmission. Out of warranty and Toyota wants to provide no help even know this is an ongoing issue with so many owners

NHTSA ID

11707494

Incident

Feb 10, 2025

Almost caused high speed accident merging onto toll road! The vehicle is experiencing a severe transmission slippage, shudder, and grinding noise, consistent with TSB-0008-21 (UA80 transmission failure). This defect causes hesitant acceleration and erratic shifting, creating a safety hazard when merging onto highways or crossing intersections. I am concerned the transmission will fail completely while driving, resulting in a sudden loss of motive power and increasing the risk of a crash. Toyota has covered this exact safety defect in 2017–2019 models (CSP ZJC) but has failed to recall the 2021 models despite identical symptoms. First reared it's head as slipping when putting vehicle in reverse, 25k+ ago. Was told by Toyota Certified mechanics it was an operator error. Morphed into larger issue.

NHTSA ID

11700698

Incident

Oct 30, 2025

Entering the freeway a mile from home the car would not properly excellerate, only reachind 40 mph before exiting the freeway in favor backroads to my appointment. Shaking back and forth while driving, exacerbated when braking and coming to stop, I needed to put the car into neutral to calm down the shaking while waiting for the light to change. I just went through experiencing a brake failure and reporting of that to this Agency and now see another of many defects associated with the 2020-2022 Toyota Highlanders and Siennas Toyota is not addressing through Recalls as they should be, and further frustrated this Agency has or chooses to have no means by which to enforce Toyota's responsibility to the public

NHTSA ID

11683905

Incident

Aug 8, 2025

My 2021 Toyota Highlander experienced transmission problems mainly related to the transmission models. My vehicles reported issues such as whining or grinding noises, which were attributed to problems with the pinion shafts in the front carrier assembly.

NHTSA ID

11670791

Incident

Mar 11, 2025

Yesterday, as I do a couple times a month, I went to switch parking places, putting my 2021 Toyota Highlander where my 2007 Mazda was parked, in order to drive it and keep the battery from dying. After starting both cars I first moved the Mazda to make room for the Toyota. As I was slowly steering the Toyota at (idle speed) into the now vacant parking spot, the car accelerated on it's own, prompting me to hit the brakes, but to no avail. The car jumped the curb hitting, knocking over and and damaging a large ceramic planter and small tree in my neighbor's yard. My split second reaction upon having no brakes and a run away car was to push it out of drive, which ended up putting the car into reverse, causing a harsh jolt, followed by the car accelerating again on it's own, in reverse towards another neighbor's garage. I live in a condo complex, so all of this took place within about 30 feet of forward/backward/forward motion. My second split second decision (with no brakes) to avoid smashing into the garage was throwing it back into drive, which sent it accelerating back towards the parking place again. This time I had the presence of mind to push the power button on the dash, allowing me to barely come to stop before jumping the curb again. Whole thing lasted about 15 seconds. I had an appointment to attend, so after a brief conversation explaining to my (now outside) neighbor what happened, I left in the older car. Returning later in the day I found damage to the front of my Toyota and wonder if my transmission is damaged as well. I'm reimbursing my neighbor today. I've not attempted to drive the Toyota since, and am seeking your advice on how best to proceed, whether I should initiate contact with Toyota regarding this incident, or is that something you should initiate? Please advise. Thank you.

NHTSA ID

11666931

Incident

Jun 13, 2025

I am seeing a transmission slip and also engine whining noise. There is a widely known issue with this transmission failing. My serial number A3A20M01780 falls right outside the scope of the TSB issued by Toyota for these transmissions.

NHTSA ID

11664736

Incident

Jun 2, 2025

My 2021 with 73000 miles is now at a dealershop 700 miles away from home. I didn't drive far while away but a week into my vacation, i started hearing a whining sound upon accelerating. Sound seemed to get louder on second day of hearing the sound. Took it to a dealership in the Leesburg Virginia area....they charged me 203.00 for diagnostics and indicated need new transmission for near $11,000. Each time I went to my dealership in my area for an oil change, they indicated that I needed a transmission fluid change. I read that when Toyota installed a "Sealed Transmission System" these changes would not be needed or at least limited.... Because the so call system is sealed, only dealership techs can check your fluid levels. How do you know if, when they check it, do they replace what they took out and if they do this regularly and don't refill what they took out, your fluid would eventually be pretty low...there is no way to check because "Sealed Transmission System" is only check by the dealerships (no transmission fluid dip stick on 2021 highlanders (and 2022, 2024, 2025). So you can't check it like an oil dip stick. We're [XXX].....INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11662993

Incident

May 14, 2025

My 21 Highlander has a wine noise coming from the transmission. There is currently a bulletin out by Toyota T-SB-000821 confirming that the transmission in this model needs to be replaced. I took my car to two separate mechanics who confirmed the noise is coming from transmission. I called Toyota this morning. Spoke with a lady and she told me she cannot locate the bulletin on my VIN number so pretty much there’s nothing they can do to help. I’m having the issue with my car that Toyota is aware about and has put out a bulletin regarding the issue. I think Toyota needs to take care of this. This is not something that should be VIN specific if I’m having the issue then fix it! At least send me to a Toyota dealership for you guys to confirm the issue and fix it!

NHTSA ID

11661415

Incident

Jan 1, 2025

TRANSMISSION, Jolts when backing up, and hesitates in traffic. The dealership confirmed it's the transmission. No warning lights, just running poorly with hesitation, afraid of breakdown. First appear a month ago after my warranty expired. I have a 2021 Highlander with 80,000 miles and still owe $22,992.84 on the vehicle. My warranty 60/60,000 is of is not any good. The issues is the transmission. The dealership is telling me it's not covered even though this is an issue with this model. For a another $11,000 they can install a new transmission. Toyota you are better then this, my Camry I had almost 300,000 on it. I had another highlander before this one. Very disappointed.

NHTSA ID

11652631

Incident

Apr 3, 2025

The vehicle pulls/jolts foward as I slow down at a stoplight. At first, I thought this was normal, but over the past year, I've noticed something unusual, possibly with the gear shifting. It has become more noticeable over time. It has happened enough where I almost get into a fender bender with the car in front of me. I started researching this issue and it's a common complaint among other Highlander vehicle owners. [XXX] . I reported this issue to the Toyota Dealership and all have stated this was normal. I have also seen other issues with the transmission with the similar year and build. Leading me to believe this car may have an early sign of transmission issues. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11627717

Incident

Nov 27, 2024

My car out of no where once it hit 60k miles (which makes it fall off warranty) I start having transmission problems. It’s a 2021 which is very weird for that to happen. Bought it brand new. I was driving with my kids in the car on the highway and the car decelerates and I freaked out. I see that I’m not the only one that is having this issue and it looks like it’s 2020-2021 models that are having transmission issues and I think this needs to be something to get checked. Automatically after driving the car decelerates and you don’t know where or when it can be the rpm drops. Took it to the dealership they said it’s transmission but a brand new car right when it hits 60k miles then this happens.

NHTSA ID

11626547

Incident

Nov 5, 2024