2018 Toyota Sienna transmission problems

Filed Nov 6, 2026 · Transmission · AZ

Since 2018–2019, our 2018 Toyota Sienna has had recurring drivability and suspected transmission problems, including stalling, failure to engage or accelerate when the accelerator is pressed, rough idle, hesitation, and harsh shifting. We reported these concerns to Toyota and filed an the federal safety agency complaint during our first year of ownership. The problems have continued intermittently for years and now include transmission whining, slipping, delayed gear engagement, irregular shifting, and reduced power. Unexpected stalling or failure to accelerate creates a safety risk when entering traffic, crossing intersections, or avoiding hazards. On October 19, 2026, AAA inspected the vehicle following a four-wheel-drive malfunction warning. Its October 20 invoice documents UA80F eight-speed transmission-related fault codes P0740-7E, P2713-7F, and P2756-7F and notes possible sticking valve-body solenoids. Toyota's own Technical Service Bulletin T-SB-0160-18 (issued December 17, 2018; revised May 11, 2021), titled "Transaxle Whine Noise, Harsh Shift, MIL ON, or Reduced Power," applies to certain 2017–2018 Siennas and lists these exact three codes (formatted P07407E, P27137F, P27567F). Toyota's Customer Support Program ZJC, Policy Bulletin POL19-04 (2019), also acknowledges transmission whine, harsh shifting, reduced power, and warning lights in certain UA80-equipped vehicles and describes a possible assembly defect involving a washer tab and loosening internal nut. An authorized Toyota dealer evaluated the vehicle October 24–30, 2026, after receiving AAA's findings but reported it could not reproduce a warning light and that the VIN/transmission serial number were outside program limits. No transmission repair was performed. The vehicle remains unrepaired. Please investigate whether this longstanding safety-related failure affects vehicles beyond Toyota's stated production cutoff.

Filed Sep 22, 2026 · Transmission · MI

Whining noise when accelerating, transmission shop reported discovery of damage to transmission upon removal and inspection of transmission.

Filed Sep 17, 2026 · Transmission · MI

Transmission whining above 20mph. Toyota customer care program [XXX] states my vehicle falls within timeframe but dealer and corporate will not honor repairs INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Jul 14, 2026 · Transmission · FL

Vehicle: 2018 Toyota Sienna XLE AWD, VIN [XXX], approximately 112,000 miles. Component: Power Train / Automatic Transmission (UA80F 8-speed). The vehicle has developed a pronounced whining noise from the transmission that rises with road speed, accompanied by harsh/rough shifting. A Toyota dealer inspected the vehicle and diagnosed a failing transmission requiring replacement. The symptoms and diagnostic trouble codes match those described in Toyota TSB T-SB-0160-18 ("Transaxle Whine Noise, Harsh Shift, MIL ON, or Reduced Power") for the UA80 8-speed transmission. This is the same failure mode Toyota acknowledged in Customer Support Program ZJC, which attributes the defect to a washer/locking tab that was not sufficiently bent during assembly, allowing an internal nut to loosen and causing progressive internal damage. However, this vehicle's transaxle serial number falls outside the range covered by ZJC, so Toyota has not provided coverage despite the identical defect and symptoms. This represents a safety concern. Based on documented failures of this transmission across the UA80 platform, the condition can progress to loss of power, limp mode, or sudden loss of forward propulsion while driving — including at highway speed and without further warning — creating a risk of a crash or of being stranded in traffic. The vehicle has been maintained through authorized Toyota service. I am requesting that the federal safety agency investigate whether the UA80/UA80F transmission defect warrants a broader safety defect determination and recall, given the volume of similar complaints across affected model years INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Jun 21, 2026 · Transmission · CA

Since owning my 2018 Toyota Sienna, I have experienced hesitation and erratic shifting with my transmission. I have the UA80E transmission which upon research others are experiencing issues with as well. It appears Toyota is not fully acknowledging the problem. The problem is a safety issue as sometimes when you go to quickly accelerate (merging, making a turn while starting from a stop, etc) the transmission hesitates and doesn't engage for a few seconds. This is an ongoing problem with the transmission. Toyota really needs to fix these transmissions!

Filed Feb 23, 2026 · Transmission · WI

My 2018 Sienna had developed a whining noise when accelerating. After taking it in to the mechanic, they advised the transmission was failing. Estimated price tag of $6500-7000 to repair. The vehicle has less than 140K miles. Looking at different issues with this make/model and year, it seems like its rather common. I bought a Toyota for its reputation of getting at least 200K if not more miles. I called both the dealer and Toyota themselves. Both said too bad, so sad - nothing they could do for me.

Filed Feb 2, 2026 · Transmission · 126,000 miles · SD

The contact owns a 2018 Toyota Sienna. The contact stated that while driving 30 MPH and ascending a hill, the vehicle started making an abnormal whining sound and hesitated while accelerating. The vehicle was driven to the dealer to be diagnosed. The vehicle was diagnosed with transmission failure. The manufacturer was notified of the failure. The failure mileage was approximately 126,000.

Filed Jan 16, 2026 · Transmission · CT

Transmission has been whining. A P27137F Code appeared and the vehicle is only in 2WD mode currently. Concerned to drive vehicle due to further damaging transmission or getting stuck while on the road.

Filed Jan 2, 2026 · Transmission · TX

My husband and I bought this van brand new 6 years ago. We have taken very good care of it and have had it serviced only at the dealership. We haven’t had any problem with the van outside of regular maintenance. On 10/29/25, I had a van full of children when I felt a slip in my acceleration and a warning light came on that read, “ A malfunction in the electronic control of the engine, throttle, or automatic transmission has been detected. Contact your dealer in order to have your vehicle inspected immediately.” Thankfully, I was able to get it to the parking lot. The van didn’t leave that parking lot until the next morning when we took it directly to the dealership. That is when we were told the solenoid and the transmission had gone out. We had to have the whole thing replaced. The van only had 89,388 miles on it.

Filed Aug 4, 2025 · Transmission · WA

Transmission Whine and Hesitation. Low gear it will hesitate from stop. Know issue with this transmission. There should be a recall on all ua80 transmissions.