Volvo 240 Back Up Light Bulb Size

The Volvo 240 back up light utilizes a P21W bulb size for the rear lighting assembly. Data for the specific bulb requirements covers the range from 1990 to 1993.

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
1990-1993	P21W

Bulb Specifications

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

Other Locations

Additional Notes

The Volvo 240 uses the P21W bulb for its back up light across the 1990-1993 model years.
The P21W is an ECE-standardized bulb type, meaning it conforms to European and international automotive lighting regulations rather than SAE standards used in North American domestic applications.
As a single-filament bulb, the P21W serves one dedicated function per housing, which in this application is the reverse light circuit.
The P21W operates at 12 volts and draws 21 watts, placing it in the mid-range of standard automotive signal bulb wattages.
The BA15s designation refers to a single-contact bayonet base with a 15mm collar, distinguishing it from the BA15d, which carries two contacts. Substituting a dual-contact base bulb into a single-contact socket is not compatible.
The "s" suffix in BA15s specifically indicates a single offset pin, and the physical pin arrangement determines whether a bulb seats and makes proper electrical contact in a given socket.