2018 Toyota Highlander engine problems

“While driving, my vehicle experienced a severe and sudden failure of the Aisin UA80F 8-speed automatic transmission. The transmission exhibits erratic and hard shifting, severe hesitation, and a dangerous delay in acceleration when trying to merge into traffic or accelerate from a complete stop. Frequently, the engine revs high, but the transmission fails to engage the gear promptly, resulting in a sudden, violent lurch forward when it finally catches. Furthermore, the vehicle intermittently loses motive power entirely while in motion, forcing me to coast to the side of the road. A loud, high-pitched whining noise is audible from the transmission assembly, and diagnostic checks indicate internal mechanical overheating and premature component wear.”

“The UA80 transmission on my 2018 Toyota Highlander Limited AWD began the "death whine" at 110,000 miles. Brought it directly to a Toyota dealer and was told the transmission needed full replacement. Seems to be very common with these transmissions and there's a service bulletin that's advertised from Toyota (our VIN number was not covered despite the exact same issue described to a T).”

“My transmission had to be replaced at 30,000 miles and a year and two weeks later it needs replaced again at 42000 miles. Toyota will only cover 1/2 the replacement the second time and nothing the first.”

“While driving my 2018 Toyota Highlander Limited, the check engine light began flashing off and on. I was near an exit and drove off the freeway. I could feel the car (near the gas pedal) start shaking, then the power went down quickly... as I was trying to find a safe place to go. The farther I drove, there was less power until the car was going about 2 miles an hour. The check light continued flashing as I pulled into a parking lot. This was very scary as I'm sure the car would have just stopped on the freeway if I had not been near an exit as it just simply had no power left. (The check engine light has been on over a year and I took it to three different mechanics. Not one could fix it. This car wiped out my savings and now sits at a Toyota dealership)!”

“I just got my vehicle inspected and successfully passed with no codes on 07/07/2026. Today 07/10/2026 as I was driving to work my vehicle began to jerk/ jitter and when into limp mode. I took it to a shop to have the codes checked on it and they said it was something to do with the transmission and they don’t specialize in that type of work. My vehicle has less than 45400 miles on it and been maintained regularly. I was told this was a common issue with these vehicles. I don’t know where to go to get this serviced. I called around to local shops with no luck at getting someone to fix or look at the cause of it.”

“Engine cam tower oil leak due to the manufacturer's inadequate assembly of the engine parts. The mating surfaces were not adequately prepared and/or application of a contaminated sealant did not adhere to the surfaces creating a small oil leak that eventually became larger and finally noticed. The Car Care Nut automotive shop performed this repair and documented in the video: [XXX] The 2018 engine (3.5L DOHC V6 D-4S Engine with Dual VVT-i Direct Shift) with 52,500 miles has by now (2024) developed a large oil leak coming from the cam tower seal, and requires replacement. I'm the original owner with the car always being garaged and maintained by the book at the dealer. Toyota of America is refusing any assistance with the defective engine component even though it is under the 60,000 miles powertrain warranty, but past the 60 months warranty period. The leak likely has been there since leaving the factory floor, but was not noticeable until after five years of use. Leaking engine oil on hot components of the engine bay may result in smoke, burning odor, and even fires. This vehicle has a concurrent vehicle safety complaint NHTSA ID Number: 11611353”