The BMW ActiveHybrid 3 brake bulb utilizes a P21W size for outer brake applications and an H21W size for inner brake functions. The replacement chart covers vehicle production years spanning 2013 to 2015 with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The BMW ActiveHybrid 3 uses two bulb types across its brake lighting positions for the 2013-2015 model years: P21W and H21W.
Both the P21W and H21W are ECE-standard single-filament signalling bulbs rated at 12V and 21W, making them identical in voltage and wattage.
The primary distinction between the P21W and H21W lies in their base type. The P21W uses a BA15s bayonet base, while the H21W uses a BAY9s base, making the two bulbs physically non-interchangeable.
The inner brake position on the BMW ActiveHybrid 3 takes the H21W bulb across all three model years covered in the specifications.
The outer brake position uses the P21W bulb across the same 2013-2015 span.
A third brake position, listed without a sub-part label, also specifies the P21W bulb, though it carries an "Adaptive" designation for all three model years.
The "Adaptive" designation on the unlabeled brake position indicates the system adjusts its behavior based on driving conditions, which is a function of the vehicle's electronics rather than the bulb itself.
Because the H21W and P21W share the same wattage but differ in base configuration, substituting one for the other is not possible without a base adapter, and even then compatibility with the vehicle's socket is not guaranteed.
Both bulb types conform to ECE regulations, meaning they meet lighting standards recognized across Europe and many other markets worldwide.
The P21W with a BA15s base is a widely used automotive signalling bulb, whereas the H21W with its BAY9s base is less common, which may affect parts availability depending on the market.