Chevrolet Cobalt Back Up Light Bulb Size

The Chevrolet Cobalt back up light requires a 921 bulb size for proper installation and function within the rear lighting assembly. Data for the specified component covers the range from 2005 to 2010.

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	US Type	EU Type	Shop
2005-2010	921	W16W	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921	Check Price

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Additional Notes

The Chevrolet Cobalt uses the 921 bulb size for the back up light across all listed model years, spanning 2005-2010.
The 921 bulb follows the ANSI standard, which is the recognized specification system used in the United States and Canada for automotive lighting.
This bulb belongs to the T15 form factor, a wedge-type base that connects by friction fit rather than by a twist-lock or pin mechanism.
The 921 operates at 12 volts, consistent with the standard electrical system voltage found in passenger vehicles.
The bulb carries a 16-watt power rating, which reflects the amount of electrical energy it consumes during operation.
The wedge base design of the T15 means the bulb is held in place by the socket walls themselves, with the filament leads bent along the base to form the electrical contacts.
Because the 921 is an ANSI-standardized bulb, it is produced by multiple manufacturers to the same specification, meaning physical and electrical compatibility is consistent across brands carrying that designation.