I have a couple of LG dishwashers, both indicating pumping faults according to the error codes.
Basically they run for about 5 minutes with the drain pump running, no water in machine, no blockages, checked all machines components all seams ok, then flashes error code.
If it’s the dishwashers I would refer the customer to LG to be honest, they have a mod kit for the pcb’s which isn’t available to anyone but their own appointed “upgrade network”, it was NESN but I don’t know if they are still doing the work.