CKP vibrochen sensor

Crankshaft position sensor - CRANKSHAFT

The crankshaft position sensor measures the rotational speed (RPM) and precise position of the engine crankshaft.

Without a crankshaft position sensor the engine would not start.On some machines, the sensor is installed close to the main pulley (harmonic balancer).

In other cars, the sensor could be installed in the transmission housing or engine cylinder block. In the technical literature, the crankshaft position sensor is abbreviated CKP.

 

How the crankshaft position sensor works

The crankshaft position sensor is positioned so that the teeth on the reluctor ring attached to the crankshaft pass close to the tip of the sensor. The reluctor ring has one or more missing teeth to provide the engine computer (PCM) with the reference point at the crankshaft position.

As the crankshaft rotates, the sensor produces a pulsed voltage signal, with each pulse corresponding to the tooth on the reluctor ring.
The PCM uses the signal from the crankshaft position sensor to determine when to spark and in which cylinder. The crankshaft position signal is also used to monitor if any of the cylinders misfire.If the signal from the sensor is missing, there will be no spark and the fuel injectors will not operate.

The two most common types are magnetic sensors with a pick-up coil that produce A/C voltage and Hall-effect sensors that produce a square-wave digital signal. A pick-up coil sensor has a two-pin connector. The Hall-effect sensor has a three-pin connector (reference voltage, ground and signal) - modern machines use this type of sensor

Symptoms of a defective crankshaft position sensor

A faulty sensor can cause intermittent problems: a car may stop or lock randomly, but then restart without any problems. The engine may have trouble starting in wet weather, but start fine afterwards. Sometimes you may see the RPM indicator behaving erratically.

In some cases, a sensor failure can cause a long delay before the engine starts.

Crankshaft position sensor problems

The most common OBDII code related to the crankshaft position sensor is P0335 - Circuit "A". In some cars (e.g. Mercedes-Benz, Nissan, Hyundai, Kia) this code is often caused by a faulty sensor, although there could be other reasons, such as wiring or connector problems, damaged reluctor ring, etc. Intermittent locking can also be caused by a problem with the crankshaft position sensor wiring. For example, if the sensor wires are not properly secured, they can rub against a metal part and short out, which can cause intermittent locking.

Chrysler Bulletin 09-004-07 describes a problem with some 2005-2007 Jeep and Chrysler models in which a faulty crankshaft position sensor can cause a starting problem. The sensor will need to be replaced with an updated part to correct the problem.
Another Chrysler Bulletin 18-024-10 for some 2008-2010 Chrysler, Dodge and Jeep vehicles mentions a problem where the code P0339 - Intermittent Crankshaft Position Sensor may be caused by an improper offset or improper pad.

Crankshaft position sensor failures were common in some GM cars in the 1990s. One of the symptoms was stalling when the engine was hot. Replacing the crankshaft position sensor usually solved the problem.