A crankshaft position sensor is a device that uses a magnetic field to sense or read the position of the crankshaft as it rotates. Data related to the position of the crankshaft is passed along to the engine’s main computer, the Engine Control Module, or ECM.
In order for your engine to run properly, each of its internal components must move together in concert the way instruments play along with one another in an orchestra. Synchronized by the timing belt, the crankshaft, pistons, valves, and camshaft(s) all need to play together at the same time and in relationship to the fuel injection and ignition systems. One of the ways it does so is through the use of two types of sensors, one for the camshaft and the other for the crankshaft.
Mounted near the bottom of your engine where the crankshaft protrudes through the engine block, the crankshaft position sensor sends information about the position of the crankshaft to the ECM. There it is used to determine the relationship of the crankshaft to the camshaft(s). If they are not timed correctly, the ECM makes adjustments to the fuel injection and ignition systems to make sure your engine runs at maximum efficiency and power, and to avoid internal damage and premature wear.
Since the crankshaft position sensor is located near the bottom of your engine, the most effective way for a technician to gain access is from underneath. Therefore, a technician will likely lift and support your vehicle in the air and remove any shields or guards that are in the way. The connector from the wiring harness is then unplugged from the sensor and the mounting fasteners are removed. Care must be exercised as the technician dislodges the crankshaft position sensor from the engine. A fresh o-ring seal is prepped and installed on the new sensor, the sensor is mounted and fastened inside the engine, and the wire is connected.
Once all components are back in place and your vehicle is back on the ground, the technician will clear any related engine trouble codes with a scan tool and verify that the repair was successful.