A crankshaft position sensor is an electronic device used in an internal combustion engine, both petrol and diesel, to monitor the position or rotational speed of the crankshaft. It is one of the two most important sensors in modern-day engines, together with the camshaft position sensor. The crankshaft position sensor monitors as a multifunctional sensor used to set ignition timing, detect engine RPM and relative engine speed. It is positioned so that teeth on the reluctor ring attached to the crankshaft pass close to the sensor tip. The reluctor ring has one or more teeth missing to provide the engine computer with the reference point to the crankshaft position. As the crankshaft rotates, the sensor produces a pulsed voltage signal, where each pulse corresponds to the tooth on the reluctor ring. The control unit uses the signals to calculate speed and position of the crankshaft in order to gain important basic data for injection and ignition timing.
A faulty crankshaft position sensor can cause the following symptoms:
- Check engine light comes on
- Engine not starting
- Poor performance
- Engine stalling
- Increased fuel consumption
- Inconsistent acceleration
- Sudden drops in RPM
Common causes of failure can be:
- Over time, any sensor can wear out and fail
- Exposure to high temperatures can cause the sensor to fail
- Exposure to oil or other engine fluids can cause the sensor to fail
To troubleshoot a faulty crankshaft position sensor, it is essential to know which type of transmitter is involved. Direct checks on the crankshaft sensor can be difficult if the exact design type of the sensor is not known. Before the checks, it must be clear whether the sensor is an inductive sensor or Hall generator.
