Genuine OEM Audi Crankshaft Speed Sensor Ring, part number 028105189B. This precision-machined metal ring is a vital component of the engine's speed sensing system, providing accurate rotational speed information to the engine control unit (ECU). It works in conjunction with the crankshaft position sensor to determine engine RPM and piston position, which is crucial for ignition timing, fuel injection, and overall engine management. The ring is designed for exact fitment on the crankshaft. Choosing a genuine OEM sensor ring ensures precise tooth geometry, material integrity, and reliable signal generation for optimal engine performance and diagnostics.