Skip the 2017. Hunt the 2020 — or the 2023 if you want the hybrid.

The eight-speed's first year. 152 complaints, double any other year here, and about a third of the recent filings are the same story: the new UA80 eight-speed automatic whining on acceleration, then hunting gears, then failing — reported at 78,000, 112,000, 120,000 and 138,000 miles. Toyota's own bulletin blames a washer tab inside the transmission that was not bent properly during assembly, and it opened a support program (ZJC / POL19-04) for 2017 and 2018 vans. The catch is that the program is scoped by VIN, and the most common grievance in the federal file is being told your van is not on the list. Owners quote $9,260.84 and $11,000 to replace the unit. Buy a 2017 only with a documented transmission fix, or after a dealer has confirmed your specific VIN qualifies — and verify recall 18V-211, the brake booster vacuum pump that can cause a sudden loss of brake assist.

The redesign, with a brake habit. 202 complaints, the largest file in this range and a launch year. The mechanics are not the problem — the independent Toyota mechanic in our sources went through one on delivery day and found nothing new under the bonnet. The problem is braking: owners describe the pedal briefly going soft as the van hands over from regenerative braking to the ordinary brakes, surging forward before the brakes catch, worst downhill and into corners. Toyota issued a brake control module software update in May 2024 and owners report the surge returning afterwards. Add an open passenger-airbag-sensor recall (23V-865) whose parts backlog pushed owner letters into January 2026, and this is the fourth-generation year to approach with a long test drive.

The quietest file, and the last V6. 36 complaints — the smallest count of any Sienna year we cover — and two recalls, one of which belongs to a wheelchair-conversion company rather than Toyota. This is the last Sienna with the V6, the eight-seat layout with a genuinely removable second row, and no hybrid system to think about, and the independent mechanic in our sources names it a play-it-safe year. Two things to check. The eight-speed is the revised unit, but two of those 36 filings are outright failures in the mid-eighty-thousands with a $9,000 quote, and Toyota's transmission program stops at 2018 — so drive it and listen for a whine. And the sliding-door settlement also stops at 2018, so every cable, hinge and latch on a 2020 is your bill.

The last good six-speed. 75 complaints and the drivetrain our mechanic source calls trouble-free: 'if you have a 2011 to 2016, zero problems.' He names 2015 and 2016 as the best years to buy for exactly that reason — this is the last Sienna before the eight-speed. The price of admission is doors and leaks. Recall 16V-858 covers power sliding doors that can open unexpectedly while the van is moving, and the class-action programs that pay for cables, hinges and latches run ten years from the van's first day in service, which on a 2016 is expiring now. Get it on a lift and check the front timing cover and the head gasket, both of which leak on this V6, and check the water pump for a rattle.

The cleanest hybrid year. 62 complaints, the smallest fourth-generation file, and just two recalls — one a bolt-tightening job on the third-row seatbacks, the other applying only to wheelchair conversions. A 40,000-mile independent long-term test logged exactly one unscheduled repair over the whole distance, a sensor cover replaced under warranty. Two things to test rather than take on trust: the same brake surge that runs through this generation, which is still about four in ten of this year's complaints, and the roof and rear glass, which shatter without impact often enough to form a small cluster. Also ask about Toyota's high-voltage cable corrosion program 22TE09 — its published symptom is AM radio static.