Saturn L100 Back Up Light Bulb Size

The Saturn L100 back up light requires a P21W bulb size for proper installation and function within the rear lighting assembly. Data for 2001 through 2002 provides the specific information regarding the required components for the vehicle.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
2001-2002	P21W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

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Additional Notes

The P21W is the specified back up light bulb for the Saturn L100 across its 2001-2002 model years.
The P21W follows the ECE (Economic Commission for Europe) standard, a regulatory framework used across Europe and numerous other markets worldwide.
This bulb operates on a 12-volt electrical system and draws 21 watts, which is typical for single-filament automotive signalling applications.
The P21W uses a BA15s bayonet base, a single-contact mount where the "s" denotes a single pin, distinguishing it from dual-contact bayonet variants that are not interchangeable with this fitment.
As a single-filament bulb, the P21W is designed for functions requiring only one light output state, consistent with its use in a back up light application.