Buick Reatta Back Up Light Bulb Size

The Buick Reatta back up light requires bulb size 890 for the specific lighting component located at the rear of the vehicle. Data for the bulb size covers the range from 1988 to 1991.

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
1988-1991	890

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament halogen bulb with PG13 base. 12V, 27W.	890

Other Locations

Additional Notes

The Buick Reatta uses the 890 bulb size for the back up light across all documented model years, spanning 1988-1991.
The 890 is an ANSI-standardized bulb type, meaning its specifications are governed by a recognized North American standard applicable in both the United States and Canada.
The 890 bulb operates on a 12-volt electrical system, which is consistent with standard automotive DC voltage.
At 27 watts, the 890 produces a moderate output level typical of incandescent-class reverse lighting applications.
The 890 uses a single filament, meaning it serves one lighting function only and is not designed for dual-intensity operation such as combined stop and tail duties.
The PG13 base is a prefocus-type base, which positions the filament at a fixed point relative to the base to ensure consistent light projection within the lamp housing.
Because the PG13 base is a prefocus design, substituting a bulb with a different base type would alter filament positioning and may affect light output alignment in the Buick Reatta (1988-1991) housing.