Camshaft Position Sensor

The crankshaft sensor gives engine speed and position, but the crankshaft turns twice per combustion cycle. The camshaft sensor resolves which of the two turns is the compression stroke, so the control unit can time sequential injection and ignition correctly.

Most sensors are Hall-effect types reading a toothed wheel or notches on the camshaft. On engines with variable valve timing, the control unit also uses this signal to measure the actual camshaft angle and compare it with the target. Most engines use Hall-effect sensors that read a toothed wheel or marks on the camshaft. Engines with variable valve timing often have one sensor per camshaft so the control unit can measure each one’s actual position.

As the target wheel passes the sensor tip, the sensor switches its output on and off. The control unit compares this pattern with the crankshaft signal. By comparing camshaft and crankshaft signals, the control unit checks that the timing chain or belt has not jumped and that variable valve timing reaches its target.

A failing sensor or wiring can cause hard starting, stalling and codes like P0340. Correlation codes between camshaft and crankshaft can also point to a stretched timing chain, not the sensor itself. A faulty signal can cause hard starting, stalling or reduced power, and stores codes in the P0340 range. Because a stretched timing chain can produce similar codes, the sensor should not be replaced without checking the timing first.