Same problem
I just replaced the fuel sending sensor on my 13 3500HD and still have the same problem. I've checked the grounds on the truck and cleaned the connections on the PCM and BCM. Truck is full of diesel but only reads 1/4 tank for a few seconds then empty. I get a random code each time I clear it but haven't ran it long enough to get an SEL. Any one else ran into this issue and found the problem.