What does the crankshaft position sensor monitor?

The crankshaft position sensor plays a critical role in engine management by providing precise information about the crankshaft's rotation. It monitors the RPM (revolutions per minute) of the crankshaft and determines its position in degrees of rotation. This data is essential for the engine control unit (ECU) to manage various functions, including fuel injection timing and ignition timing. By knowing the crankshaft's position, the ECU can optimize engine performance, improve fuel efficiency, and reduce emissions.

In contrast, the other options address different aspects of engine performance that do not relate directly to the function of the crankshaft position sensor. Engine temperature, fuel level, and air intake temperature are monitored by separate sensors designed specifically for those purposes. Thus, option B correctly identifies the primary function of the crankshaft position sensor, central to the overall operation and efficiency of the engine.