Have a 2006 lly or lbz so I'm told duramax that's throwing a P0087 code and a P1631 code. Anyone have any ideas as to what the problem could be. Also has a Banks economind tuner and speed brake for towing. Usually it with throw the code P0087 with a heavy load. Then I have to stop to clear the code and it is good until next time. These mods have been installed on the truck around 110k and has 190k now.

 

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