Toyota Sienna 2021–2023 — technical service bulletin
Bulletin T-TT-0725-23 · NHTSA communication 10234336 · issued Mar 23, 2023
Technical service bulletin
communication type
Back Over Prevention
component
2021–2023
model years
3
vehicle entries
Official summary
TT: Some 2021- 2023 Sienna HV vehicles may duplicate an abnormal noise (Growl, Humming and/or other) from the Hybrid T/A at various vehicle speeds and normal drive conditions. Please contact TAS for diagnostic instructions to aid in resolution of the condition.
Vehicles covered
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.