P0641 Code 2019 Suburban

[Cut Wagon]

So a little history. Friday I changed the transmission fluid and filter. No issues. Saturday towed boat drove 2 hrs back home in heavy rain storm. P0641 popped during drive in rain. I didn’t notice any performance issues with the code being thrown. MPG was normal etc. So I’ve read up a little and know it’s a short somewhere. By chance is this common on our generation of Hoe’s and Burbs?

I’m going to start with checking connections battery etc for tightness and corrosion, then clearing the code and see if it comes back.

 

[Cut Wagon]

Oh, I don’t know what section this should be under, plenty of possibilities.

 

[Cut Wagon]

Code hasn’t returned as of now.‍

 

[Cut Wagon]

Well the 6041 came back. It’s a 5v circuit that has 7 sensors on it. I was able to verify 6 of the 7 sensors were getting 5v. All 6 of them under hood. Fuel tank sensor I was saving for last. Since accessing the camshaft position sensor was a pia, and it was only $37 OEM part, I changed it out. I did get a P0341 recently with the 6041. So with new camshaft sensor I have no codes and it runs pretty good. Not calling it solved just yet bc I’ve only gone about 100 miles. We’ll see how it goes.

 

[Fless]

Consider doing a quick CASE relearn to sync the cam and crank sensors, since you changed one. You may not notice a difference but it might save some grief in the future.

 

[Cut Wagon]

I disconnected the negative battery terminal for 10 mins. Is that the CASE relearn?

 

[Fless]

No, generally a bi-directional scanner is needed. It goes something like shown below.

Crank Relearn Instructions (With and Without an OBD Scanner/Reader) | Car OBD Diagnostics, ECU Chip Tuning & Auto Repair Support

 

[Cut Wagon]

Is that for camshaft sensor or crankshaft sensor?

 

[Cut Wagon]

Solved, I guess…ha. So I’ve gone about 1200 miles after replacing the ECM and that seems to have fix it. I checked all the sensors/connectors. Traced every harness/wire as best I could. Have probably 40 hours of my own labor into trying to fix this P0641. Couldn’t find short. Couldn’t replicate it either. Completely random P0641 comes and goes. So I gave up and brought it to the first mechanic. He kept it for a week and said he couldn’t get the code to trigger again after he cleared it and went on test drive. Cost me $380 and still had code return the next day. Then brought it to another mechanic and they said it was the ECM. Even though everything you read says it’s rare for P0641 to be the ECM. So all together it was $1200 b/t the two shops. 1200 miles later and no codes.

 

[Fless]

Is that for camshaft sensor or crankshaft sensor?

I didn't see what you wrote until now since I wasn't tagged or quoted. Anyway, it's done to correlate the crankshaft sensor position to the cam position. When your mechanic changed the ECM he would likely have needed to do one, but it wouldn't hurt to ask him if he did. Not doing one can cause intermittent long cranks and weird misfires.

 

[Cut Wagon]

Oh ok. I never touched the crankshaft sensor. It isn’t on the ref circuit a. Just camshaft sensor was changed.