The Toyota Yaris iA back up light requires a bulb size of 921 for the rear lighting assembly. Data for the specified vehicle covers the range from 2017 to 2018.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 921 bulb is the sole bulb type specified across all back up light positions for the Toyota Yaris iA, covering the 2017-2018 model years.
The 921 is classified as a wedge-type bulb with a T15 base, operating at 12 volts and rated at 16 watts.
The T15 designation refers to the bulb's tubular shape, with the numerical suffix indicating its width in eighths of an inch, making it a relatively compact wedge format common in reverse light applications.
The 921 carries ANSI standardization recognized in both the United States and Canada, meaning the specification conforms to a defined performance and dimensional standard shared across North American markets.
Both the general back up light and the inner back up light positions share the identical 921 specification for 2017-2018, indicating no distinction in bulb type between those two positions.