2020 Toyota Highlander acceleration problems

VEHICLE SPEED CONTROL

The vehicle is a 2020 Toyota Highlander experiencing a transmission system malfunction, specifically involving the automatic transmission and/or torque converter. Component/System Failure: The transmission produces a noticeable whining noise during acceleration and exhibits abnormal shifting behavior, including hesitation and delayed response when pressing the gas pedal. The issue appears to originate from the internal transmission components. The vehicle is available for inspection upon request. Safety Risk: This condition creates a serious safety concern, as the hesitation and delayed acceleration can impair the driver’s ability to safely merge into traffic, cross intersections, or respond to changing road conditions. The unpredictable response increases the risk of a collision, especially in high-speed or congested traffic environments. Reproducibility / Confirmation: The issue is consistently reproducible and occurs whenever the vehicle is accelerated. The problem has not yet been fully resolved and is in the process of being addressed with a dealership/service center. Inspections: The vehicle is scheduled to be inspected by a Toyota dealership. At this time, it has not yet been inspected by the manufacturer, police, or insurance representatives. Warning Signs / Symptoms: There were no warning lights or dashboard messages prior to or during the issue. The first symptom noticed was the whining noise during acceleration, followed by abnormal shifting behavior and hesitation. These symptoms have progressively become more noticeable over time. This issue appears consistent with reported transmission problems in similar model vehicles, raising concern that this may be a broader defect affecting vehicle safety. I took my vehicle to 3 different mechanics and they told me that my vehicle is not safe to drive long term without a total transmission replacement. Thank you!

NHTSA complaint #11728866 — an unverified report by a vehicle owner.

VEHICLE SPEED CONTROL

Vehicle: 2020 Toyota Highlander XLE Purchased: August 2020 Owner: Original owner Transmission: UA80F Dealer quote for “Transmission assembly remove and replace: $8,666.22 +tax The vehicle is experiencing delayed acceleration (lagging power) and a loud whirring noise from the transmission when the accelerator pedal is pressed. The whirring noise immediately stops when the accelerator pedal is released. The Toyota Highlander had just exceeded the 60,000 mile/5 year powertrain warranty. Vehicle has 68,079 miles and is 5 1/2 years old. The delayed acceleration creates a serious safety hazard, particularly when starting from a complete stop while attempting to make a turn into traffic. On multiple occasions, the vehicle failed to respond promptly when the accelerator was pressed, placing the vehicle at risk of being struck by oncoming traffic. On February 17, 2026, Oakbrook Toyota diagnosed the vehicle with a failed/bad transmission after charging a $200 diagnostic fee to investigate the whirring noise and power delay. This failure occurred on a vehicle that has been properly maintained and has not been modified. Upon searching the Internet, there are many, many complaints regarding the UA80 transmissions failing between 60,000 and 70,000 miles. There are also multiple lawsuits filed for failed transmissions.

NHTSA complaint #11721186 — an unverified report by a vehicle owner.

VEHICLE SPEED CONTROL

At approximately 120,000 miles, the vehicle began exhibiting a pronounced shudder or vibration between 40–50 mph under light acceleration or steady cruising. The condition progressed to delayed shifting and intermittent loss of acceleration response. The most concerning issue is hesitation and reduced acceleration when attempting to merge into traffic or increase speed. On multiple occasions, the vehicle failed to respond promptly to throttle input, creating a potential safety hazard due to loss of propulsion. The vehicle was evaluated at two authorized Toyota dealerships. Both indicated that the condition is consistent with torque converter or transmission failure. Full transmission replacement was recommended at an estimated cost of approximately $9,000. No whining or grinding noises are present; symptoms primarily involve shuddering and hesitation. The vehicle has not been driven since October 21, 2025, due to safety concerns and to prevent further damage. The vehicle has been regularly maintained at Toyota dealerships and has not been used for towing. This complaint concerns loss of acceleration, transmission shudder, and potential premature failure of the 8-speed automatic transmission.

NHTSA complaint #11719509 — an unverified report by a vehicle owner.

VEHICLE SPEED CONTROL

When coming to a stop the vehicle will often lurch forward. The lurch is powerful and could easily cause a collision. This problem occurs both when stopping in traffic and pulling into parking spaces. We were told by the dealer that the problem is caused by hybrid cars but we've had hybrid cars before that did not exhibit this behavior. It sounds like the dealership is aware of the problem but Toyota is not addressing it. This issue certainly poses a safety issue, especially for vehicles in front of the affected vehicle when attempting to stop.

NHTSA complaint #11626803 — an unverified report by a vehicle owner.

VEHICLE SPEED CONTROL

The contact owns a 2020 Toyota Highlander. The contact stated that after slowing down to come to a stop, the vehicle would inadvertently surged forward. There were no warning lights illuminated. The vehicle was taken to the dealer who was unable to determine the cause of the failure. The vehicle had not been repaired. The failure had since become more frequent. The manufacturer was made aware of the failure. The approximate failure mileage is 36,009.

NHTSA complaint #11522590 — an unverified report by a vehicle owner.

VEHICLE SPEED CONTROL

VEHICLE WENT INTO LIMP MODE REIEVED CODE P0300 REDUCED ENGINE POWER ON HIGHWAY WHEN ACCELERATING

NHTSA complaint #11387820 — an unverified report by a vehicle owner.

VEHICLE SPEED CONTROL

DRIVING 50 MILES/ HOUR VEHCLE STARTED LOOSING POWER AND STARTED TO SHAKE. ENGINE LIGHT CAME ON AND TWO DIFFERENT MESSAGES IN DASHBOARD POP OUT. ONE ABOUT HYBRID MALFUNCTION AND THE OTHER OUTPUT POWER REDUCED.

NHTSA complaint #11386179 — an unverified report by a vehicle owner.

VEHICLE SPEED CONTROL

WE RECENTLY PURCHASED OUR HIGHLANDER AND IT HAS A LITTLE OVER 4,000 MILES. TODAY WHILE DRIVING DOWN THE ROAD AT ABOUT 45 MPH, THE CAR JUST LOST POWER AND THE CHECK ENGINE LIGHT CAME ON. 1. CHECK ENGINE - REDUCED ENGINE POWER 2. SECONDARY COLLISION BRAKE SYSTEM MALFUNCTION WE HAD TO PARK AND WAIT FOR THE TOYOTA DEALERSHIP TO COME AND TOW IT TO THE SERVICE CENTER. AT THIS POINT I DON'T KNOW WHAT WAS WRONG OR WHY IT JUST CUT OUT WHILE DRIVING. I AM VERY CONCERNED AND CAN ONLY HOPE TOYOTA CAN ADDRESS THIS OR REPLACE THE CAR.

NHTSA complaint #11384736 — an unverified report by a vehicle owner.