The ECM (Engine Control Module) measures the amount of fuel to be injected in relation to the amount of air measured at any given time. Then, it forces a spark to ignite a power stroke.
The Crankshaft Position Sensor (CKP) is used to calculate the engine speed in Revolutions Per Minute (RPM) and to determine the position of cylinder one at Top Dead Center (TDC). By having the RPM and TDC, the ECM can control the precise function required for the vehicle to work properly.
If the ECM does not detect sufficient voltage from the CKP Sensor, the DTC P0337 OBDII code will be set.