2021 Toyota Sienna Hybrid Other or unknown Problems
- Complaints
- 3about this part
- Share
- 7%of 45 total for the year
- Median mileage
- —not reported
- Trend
- Not enough dataFewer than 15 complaints, too few for a reliable trend.
NHTSA recorded 3 complaints about the other or unknown of the 2021 Toyota Sienna Hybrid, 7% of the 45 complaints for this model year.
Fewer than 15 complaints name this part, so treat the figures as a rough indication only.
Example complaints
Selected from NHTSA records; personal details are removed. They are consumer reports, not findings.
“We were stopped at a stoplight. As soon as we stepped on the gas pedal, there was a loud clunk sound and plastic parts started flying out from under the car. We immediately pulled over. Oil was spilling out everywhere. The transmission oil pump was laying on the inside of the engine compartment. We had towed to Toyota. They diagnosed a bent piston went through engine which also caused a hole in the transmission. I had it towed for a 2nd opinion. Neither toyota or the 2nd opinion had ever seen anything like it. …”
NHTSA complaint #11730547, filed 2026-04“1. The rear underbody air conditioning (AC) lines and their supporting structural mounting brackets have failed due to severe corrosion. Specifically, a heavy steel mounting bracket has rusted excessively, causing localized galvanic corrosion at the point of contact with the adjacent aluminum AC lines. This structural and material failure caused the aluminum line to erode, crack, and leak high-pressure chemical refrigerant into the environment. …”
NHTSA complaint #11745261, filed 2026-06“Vehicle safety SOS button is not functioning properly. When the SOS button is depressed in case of emergency, the vehicle notifies user at the emergency system is un operational. Toyota includes this for 10 years from the date purchase and my vehicle is a 2021 making this feature active till 2031. By having the SOS button nonfunctional occupants of the vehicle, which may rely on this feature may sustain injury or death by this feature not operating correctly in the event of an accident.”
NHTSA complaint #11752014, filed 2026-07Related service bulletins
- 11028712Jan 7, 2026Some 2005 – 2026 Toyota vehicles that have undergone water intrusion may exhibit a condition in which a musty odor is present. Follow the procedures in this bulletin to remediate…
- 10249327Dec 19, 2024TT: Engine Oil Leak between the Lower Oil Pan and Crank Case
- 10252259Feb 20, 2024TSB: Some 2018 ? 2022 model year Toyota vehicles equipped with a Premium Audio with Dynamic Navigation System require a Special Service Tool (SST) USB flash drive to update the…
- 10244111Aug 17, 2023TT: A very small percentage of customers experience operational difficulties with some telematics features which they cannot resolve on their own. These resources, in conjunction…
- 10220154May 13, 2022TT: To improve customer support of telematics connected services features, additional resources have been provided in the Service Lane - Knowledge Center.
- 10183283Oct 22, 2020TSB: During the manufacturing process, tires are mounted on the vehicle as matched sets to help reduce conditions such as pulling or drifting. If the wheels are replaced or…
Other or unknown: other model years
Other parts of the 2021 Toyota Sienna Hybrid
13 complaintsBrakes
9 complaintsSeats
5 complaintsBody and structure
5 complaintsVisibility (wipers, defrost, mirrors)
5 complaintsElectrical system
4 complaintsEngine
3 complaintsExterior lighting
2 complaintsSuspension
2 complaintsTransmission and drivetrain
2 complaintsBack-over prevention (rear camera)
1 complaintsForward collision avoidance
1 complaints
← All problems reported for the 2021 Toyota Sienna Hybrid
About this data. Data from NHTSA (ODI) complaints, recalls, TSBs and investigations, updated Oct 31, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.
To check a specific vehicle for open recalls, use its VIN at nhtsa.gov/recalls. Methodology