Lexus HS 250 Hybrid 2010–2012 — technical service bulletin
Bulletin L-TT-0189-15 · NHTSA communication 10096367 · issued Oct 5, 2015
Technical service bulletin
communication type
Engine
component
2010–2012
model years
3
vehicle entries
Official summary
"tt: there has been some concern with 3 piece piston ring installations for 2az-fxe engines. This tech tip contains the accepted installation method required for lexus vehicles."
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.