EZL Sender. An engine with electronic management needs a crankshaft position sensor to monitor the position and rotational speed of the crankshaft. The vehicle’s Engine Control Unit (ECU) uses this information to control ignition timing and the fuel injection. Other information that is monitored consists of valve timing and the piston revolutions per minute. The crankshaft position sensor is commonly mounted near the crank pulley, camshaft, and flywheel or on the camshaft as well. It is one of the most important sensor in modern engines. The CPS is a common part to cause a no-start condition, and the dead giveaway of a bad CPS is that the car will start once cooled down, generally without throwing a check engine light.