2020 Toyota Sienna: What to check before buying

Transmission failure dominates these reports. Symptoms include refusing to shift, erratic acceleration, shuddering, rough running through the lower gears and a whining noise. Two complete failures arrive at about 70,900 and 85,000 miles. One had metal pieces broken off inside, and both ended with the transmission being replaced. Some failures come with no warning light or code. Others start with a check engine light or a traction control warning, and then the van barely moves. Losing drive in traffic is the main risk. A separate report describes a front axle assembly coming apart internally and leaking fluid.

Delayed fuel pump recall repairs make up most of these reports. The recall covers a low pressure fuel pump that may stop working, and the notice warns of an increased crash risk. Owners describe recall notices with no parts available and months without a fix, and one fleet van is parked until the repair is done. One separate complaint describes hesitation, rough idle and revving while parked. It ends with a van that shakes, will not accelerate and needs a tow. A $725 fuel flush and injection cleaning does not cure it.

Stalling and jerking linked to fuel pump recall campaign 20V682000 fill this category. In one report the van stalls briefly at highway speed with several warning lights on. It stalls again a year after the recall replaced the pump, and the dealer cannot duplicate the problem. Another van jerks and lunges forward under throttle at about 4,000 miles while recall parts are still unavailable. Stalling at highway speed carries a real crash risk.

Random electrical faults and warning lights make up this category. Pre-collision, lane assist and airbag warnings come back after a fuse is replaced, and the real fix is a wiring harness that is on backorder. Other reports describe blinkers turning on by themselves, radio volume changing during turns, CarPlay cutting in and out, and a brief, ear-piercing screech from the speakers. A key remote stops working, and an AWD malfunction message switches the van to 2WD mode. Dealers often cannot reproduce the faults.

Most of these complaints involve the sliding doors. A power sliding door cable binds and jams the rear door shut, and turning off the power door system does not free it. The owner notes that a federal bulletin on this issue came out in 6/2019, before the van was built. A rusted fuel door hinge breaks and keeps the rear passenger door from opening automatically. One report describes a locked rear passenger door unlocking and opening by itself overnight with no warning.

Sudden loss of power steering assist is the main pattern. It sometimes comes with stability control, pre-collision and lane departure warnings. In one case, replacing the rack and pinion does not fix it. The owner links the fault to steering recall campaign 19V532000, but the dealer shows no open recall on that VIN. Another report describes heavy steering at 55 mph with no warning light at about 6,200 miles. A third is mostly a loss of acceleration on the highway, with the engine, traction and steering lights all on.

Skidding during braking, with the ABS light on, is the serious report here. It happens during a slow turn at about 28,000 miles, along with an abnormal sound. The dealer finds a shorted front passenger side speed sensor and a fractured brake actuator. The van goes unrepaired because parts are not available. The only other complaint is about design: a narrow brake pedal that the driver sometimes has trouble finding with a foot, losing a second or two.