Lamborghini Diablo front and rear turn signal bulbs utilize a P21W size specification across all applications. The replacement chart documents bulb specifications spanning 1990 to 2001 production years.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Lamborghini Diablo uses the P21W bulb for both its front and rear turn signals across the entire 1990-2001 production span.
The P21W is an ECE-standardized bulb type, meaning it conforms to European and internationally recognized automotive lighting regulations rather than SAE standards used in North American domestic vehicles.
The P21W operates at 12 volts with a 21-watt output, which is a wattage rating typical of single-filament signaling applications in European automotive design.
The P21W uses a BA15s bayonet base, where "BA15s" denotes a single-contact bayonet fitting with a 15mm base width, distinguishing it from dual-contact variants such as the BA15d.
Because the P21W is single-filament, it serves a dedicated signaling function and is not wired to share a filament with braking or running light circuits.
The identical P21W fitment across both front and rear positions means a single bulb type covers all four turn signal housings on the Diablo, with no positional variation in specification.
The BA15s bayonet base is not interchangeable with the BAY15d or BAZ15d bases, which carry offset or dual-contact configurations despite sharing a similar physical profile.
The P21W specification remained unchanged across the full twelve model years of the Diablo, indicating no revision to the turn signal bulb fitment throughout the vehicle's production life.