DTC P041: No Cam Reference Signal From Ignition Control Module: Action

PCM turns on the "SERVICE ENGINE SOON" MIL.

NOTE: Numbers in list refer to circled numbers in diagnostic flow chart, see Fig 1. For circuit identification see Fig 2.

Check to see if Code P035 is set because a REF LO problem can cause other ignition problems.
Checking the resistance of the camshaft position sensor. The resistance should be 800-2100 Ohms. If the resistance is greater, check for an open or if it is less, check for a short to ground or each other.
Checking if CKT 631 or CKT 632 is shorted to ground.
If the sensor is able to produce a DC voltage greater than 0.2 volt the sensor is OK.
With engine running, measuring greater than 4 Hz shows that the ignition control module is producing CAM pulses.
Checking for a circuit fault or faulty ICM.

Fig 1: DTC P041: No Cam Reference Signal From Ignition Control Module Flow Chart

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC P041: No Cam Reference Signal From Ignition Control Module Flow Chart Circuit

Courtesy of GENERAL MOTORS CORP.