The Maserati 425 front and rear turn signal bulbs both require a P21W size bulb for proper operation. The replacement chart covers 1986 to 1987 model production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The P21W is the sole bulb type specified for the Maserati 425, covering both the front and rear turn signals across the 1986-1987 model years.
The P21W operates on a 12-volt electrical system and draws 21 watts, which is the standard wattage for single-filament signalling applications in European automotive design.
The P21W uses a BA15s bayonet base, a single-contact fitting where the "s" denotes a single pin offset to one side, ensuring the bulb seats in one orientation only.
The P21W is governed by ECE (Economic Commission for Europe) standards, meaning it conforms to internationally recognized regulations for signalling bulbs used across Europe and many other markets worldwide.
Because the P21W is a single-filament bulb, it serves a dedicated signalling function and is not a dual-purpose unit capable of combining turn signal and brake light duties within a single globe.
The front and rear turn signal positions on the 1986-1987 Maserati 425 share an identical bulb specification, meaning the same P21W unit is interchangeable between both locations on the vehicle.