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2001 gmc 2500hd 8.1l

Check engine light is on. Code reads CAM Sensor , however i changed out the sensor myself and it still wont go away. My truck wont start on the first two-three times and it will back fire occasionally. Any suggestions on what to do next? thanks

It’s possible the electrical connector itself is faulty. Try replacing the connector. It’s around $40 for the part.

Anytime you replace that you need to do a Crankshaft Sensor Variation Relearn. This is according to the GMC forum.

knfenimore…do you have a link available so i an read more about the variation relearn?

had a mechanic shop do the variation relearn and the code came back right after I left…

Check the connector.

the code has cleared…still backfires and wont start on first attempt…

Did you use an AC Delco cam sensor?

Did you check the 5V reference and ground?

Did you check that the new cam sensor is actually producing a signal?


I know this postime is a few years old but I have a 2001 2500hd 8.1l with the exact same issues. Did you ever get this problem resolved? If so what was it? I’ve changed the cam sensor twice, first sensor was a BTW brand I think and it gave off low input code, second sensor was ac Delco brand which gave off high input code. I left the ac Delco in and changed the crank sensor and did a relearn and still setting a engine code, doesn’t want to start right away, backfires sometimes. Pigtail seems fine