Confirm proper operation of the climate control system on all fan speeds, at all temperature ranges and at all outlets, in both front and rear seating rows. Some owners have reported problems with hot or cool air being unavailable in certain seating positions, or failure of some distribution modes to engage properly. The issue, if detected, may be the result of a bad blend door, or a bad servo in the climate control system. Here’s some more reading.

Confirm that the air conditioner is in proper working order on your test drive, too, noting that a plugged cabin air filter is a common cause of air conditioner problems. Ask the seller if they recently changed their cabin air filter. If they ask what a cabin air filter is, you’ll want to change it ASAP.

Some owners of AWD-equipped Sienna models have reported fluid leaks from the associated system hardware. Translation? Have a mechanic inspect the AWD system on the Sienna you’re considering, if equipped, for maximum peace of mind, having any detected issues remedied before your purchase. Note, further, that the Sienna’s AWD system requires regular fluid changes for proper operation and durability. Confirm that the seller has stayed on top of these fluid changes (and all others), and plan to do the same while you own the Sienna. Here’s some more reading.

Check the cruise control for proper operation, setting and adjusting it several times over the course of your test drive. A wiring short has been reported by numerous owners, which can cause the cruise control system to fail, or work intermittently. Flickering of the illumination on the cruise control stalk is a typical trouble sign as well. Here’s some more information.

Vibrations detected from beneath the Sienna have driven numerous owners batty. If you detect any, and especially if they occur typically at low revs and go away when throttle is applied, the culprit might be the catalytic converter, and specifically, some combination of the clamps and hardware that hold it in place. Here’s some more information. And a little more. Be sure to have a mechanic investigate any detected vibrations, for maximum peace of mind.

Check all rear seats for proper operation of their folding and sliding functions, ensuring each operates as expected. A third-row seat that gets stuck into its stowed position isn’t unheard of, and here’s some reading on how you might fix the problem.

Some owners have also complained of water seeping into the Sienna’s trunk or cargo area. On a test drive, spend some time pressing your hand or a rag into the rear carpeting, especially around the lower, rearward corners of the vehicle, to check for dampness, moisture, puddles and the like. Water leaks can ruin electrical components, cause nasty smells, and encourage the formation of rust. With the Sienna, a water leak into the trunk could be caused by a bad liftgate seal, a bad roof-rail seal, or an improperly installed rain gutter. Here’s some more information.

Finally, be on the lookout for clunking or popping sounds from the suspension as you travel over rougher roads at a variety of speeds. Any unwanted sounds like these typically indicate some suspension component that’s worn and in need of attention.

The Verdict: Most of Sienna’s commonly reported issues are relatively minor, easy to detect and fairly simple to repair. A well-maintained model can be bought with confidence after a mechanical pre-purchase inspection. If the unit you’re considering checks out, you’re well on your way to enjoying a spacious, flexible and reliable family hauler.

A list of recalls.

Here’s some more reading on the Toyota Sienna.

Crash Test Ratings:
IIHS: Top Safety Pick +
NHTSA: 5/5 Stars (2014 and up)

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