Googling this code comes up with a reference to power management. Like you say, there is a jumble of info related to this code. Reading some of the posts makes me think a connector was not seated totally when they replaced the active tank. You have a couple of heating circuits on the front right of the engine bay and the plugs can be a bit reluctant to "click home". I could be wrong but it would be a good starting point to check everything is plugged in, you may have to remove the fender liner to see the connections to the active tank. G/L!

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2003 4.4i black ext./black int./black headliner (kid's runabout)
2014 535d X-drive, M package, silver/black interior

Sold but not forgotten:
2009 E70 35d, black ext./black int./black headliner (sold 2021)
2006 4.8iS Le Mans blue/cream int./black headliner, SOLD in 2012 sadly...

Other hardware:
2015 Cayenne S (wife's new DD and definitely wroooommmmm)
2016 Tundra 1794 edition crew cab, luxo hauler
2005 Tundra crew cab, weekend hauler. Sold after 150k very happy miles.