The BMW 135i uses D1S and H7 bulb sizes for both high beam and low beam headlight applications, with the specific bulb size varying by production year. A replacement chart detailing headlight bulb specifications covers the 2008 to 2013 model years.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The BMW 135i carries two distinct headlamp system types across the 2008-2013 model years: HID (high-intensity discharge) and halogen capsule. Each system requires a different bulb, and the two types are not interchangeable.
The D1S is the bulb specified for 135i vehicles fitted with HID headlamps. It operates at 85 volts and 35 watts, using a PK32d-2 base with an integral ignitor built directly into the bulb unit. This ignitor is a key distinction from other HID bulb families that rely on a separate external ignitor.
The D1S is designed exclusively for projector-type housings. Installing it in a reflector-style housing produces incorrect light distribution, as the optics of each housing type are engineered around different light source geometries.
The H7 is the bulb specified for 135i vehicles fitted with halogen capsule headlamps. It is a single-filament bulb rated at 12 volts and 55 watts, mounted on a PX26d base. The single-filament construction means one H7 bulb serves one lighting function, which is why both high beam and low beam positions each list it separately.
Both the D1S and H7 are built to ECE standards, the regulatory framework used across Europe and much of the world. The H7 additionally holds approval in the United States and Japan, giving it broader regional acceptance than the D1S.
The same bulb sizes apply to both the high beam and low beam positions across all listed years of the BMW 135i, meaning the headlamp system does not use different bulb families for the two beam functions.
Because the D1S includes an integral ignitor, replacement of this bulb also replaces the ignitor component in a single step, unlike HID systems where the ignitor is a separate serviceable part.
The halogen and HID fitments represent a conditional split rather than a year-by-year change. The correct bulb for any individual 135i from 2008-2013 is determined by which headlamp system that specific vehicle was built with, not by its model year alone.