Toyota YARIS Manual page 275

NOTICE
 To prevent seat heater damage
Do not put heavy objects that have an uneven surface on the seat and do
not stick sharp objects (needles, nails, etc.) into the seat.
 To prevent battery discharge
Turn the seat heaters off when the engine is not running.
YARIS_HB_WE_52A70E
3-5. Other interior features
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