Speed and RPM sensors work to determine how fast the crankshaft is spinning. Every vehicle has its own maximum speed and exceeding this speed can do a number of negative things to the vehicle’s engine. These sensors help drivers to know how fast they are going and how much they are pushing their engine. When these sensors are faulty, it can cause problems with the vehicle’s air to fuel ratio, as well as cause troubles with the speedometer and cruise control functions of the vehicle. Quickly replacing speed and RPM sensors when they are faulty helps to ensure that the vehicle is able to fully operate without interruption or a risk to the integrity of the engine.