Elimination of the distributor in modern vehicles created the need for an alternate means of monitoring engine RPM and crank position, determining the correct spark plug firing sequence, and controlling fuel injector and ignition timing.

These functions are facilitated by the crankshaft and/or camshaft position sensor. These sensors monitor the speed of the crankshaft or camshaft, and generate a series of high- and low-voltage pulses, which represent the speed of rotation, to the vehicle’s computer. The frequency of voltage pulses increases as crankshaft/camshaft rpm increases.

The crankshaft and camshaft position sensors monitor the speed of the crankshaft or camshaft, and supply a series of high- and low-voltage pulses which represent the speed of rotation to the vehicle’s Engine Control Module (ECM). The frequency of voltage pulses increases as crankshaft/camshaft rpm increases. Sensors of this type offer the added benefit of eliminating ignition timing variations due to wear and/or backlash in the timing chain and distributor gear, as well as eliminating the need for timing adjustments.

The ECM uses these signals primarily for spark timing or fuel injector control. On OBDII-compliant vehicles, the crankshaft position sensor also serves to detect variations in crankshaft speed caused by ignition misfire. If these variations are significant or frequent enough, the ECM stores a Diagnostic Trouble Code (DTC) and illuminates the Malfunction Indicator Lamp (MIL).

Some common symptoms of a faulty camshaft position sensor are listed below. Be aware that these symptoms can occur due to various reasons, such as faulty sensor wiring, magnetic interference, worn internal components, or sensor circuitry malfunction.

a. Difficulty Starting the Engine: If the CMP is faulty, it can result in starting problems that may be intermittent or prolonged. This happens because the ECM receives incorrect timing information.

b. Rough Idling or Stalling: Inaccurate camshaft position data can cause issues such as irregular idle, engine misfire, and sudden stalling during driving.

c. Reduced Power and Acceleration: If the CMP is not functioning properly, it can cause a disturbance in the timing of fuel injection and ignition, which can result in reduced engine performance and slow acceleration.

d. Malfunction Indicator Lamp (MIL): If an issue with the CMP is present, the ECM can often detect inconsistencies in the camshaft position data and activate the MIL.

To ensure precise engine operation and performance, the Camshaft Position Sensor (CMP) plays a crucial role. It is important for vehicle owners and technicians to know of its structure, symptoms of failure, and testing/replacement procedures. This enables accurate diagnosis of engine issues and the maintenance of engine health. Faulty CMPs should be promptly replaced to maintain optimal engine performance, fuel efficiency, and longevity, resulting in a smoother driving experience. Regular maintenance also contributes to the longevity of the engine.