Crankshaft Position Sensor: Testing and Inspection
The scan tool scan tool displays 
Crankshaft Position Sensor (CKP) data as engine speed (RPM). An error in the crankshaft position sensor  circuit should set a Diagnostic Trouble Code 
(DTC) P0335, P0337, P0335, or a P0339. Refer to 
DTC P0336 CKP Sensor Circuit Performance or 
DTC P0337 CKP Sensor Circuit Low Frequency or 
DTC P0338 CKP Sensor Circuit High Frequency or 
DTC P0339 CKP Sensor Circuit Intermittent. 
Testing and Inspection