What does the ABS sensor monitor?

The ABS sensor primarily monitors wheel rotation while the vehicle is in motion. This functionality is critical for the Anti-lock Braking System (ABS), which is designed to prevent the wheels from locking up during braking. By continuously measuring the speed of each wheel, the ABS can determine if any of the wheels are about to lose traction. When the sensor detects that a wheel is slowing down significantly compared to others—indicating that it might lock up during braking—it signals the ABS control module to modulate the brake pressure on that wheel. This helps maintain steering control and stability during emergency braking situations.

Other options pertain to different vehicle systems and do not accurately represent the function of the ABS sensor. Monitoring engine temperature and fuel levels involves entirely separate sensors and systems, while brake fluid pressure pertains to the overall braking system but does not relate to the ABS sensor specifically. This distinction highlights the focused role of the ABS sensor in enhancing vehicle safety by managing wheel slip during braking.