The BMW 1600 front and rear turn signal bulbs both utilize a P21W size. The replacement chart covers 1969 through 1971 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 listed across all turn signal positions for the BMW 1600, covering model years 1969-1971.
P21W is an ECE-standard single-filament bulb rated at 12 volts and 21 watts, designed for signalling applications such as turn signals.
The P21W uses a BA15s bayonet base, which is a single-contact bayonet fitting with a 15mm collar width.
The BA15s base is non-indexed, meaning the bulb can be inserted in any rotational orientation, as it carries only a single filament with no polarity-dependent positioning requirement.
The P21W designation follows ECE (United Nations Economic Commission for Europe) standardization, giving it broad compatibility across European and worldwide vehicle applications of that era.
Both the front and rear turn signal positions on the BMW 1600 share the same P21W specification across all three listed model years, indicating no positional differentiation in bulb type.
A 21-watt rating at 12 volts produces a relatively high light output for a single-filament signal bulb, which is consistent with the visibility requirements for turn signal functions under ECE regulations.
Because the P21W is an ECE-regulated type rather than an SAE type, substitution with SAE-standard bulbs of similar wattage may not produce equivalent base fitment or light output characteristics.