Sud indicates excess foam in documented LG front-loaders. The machine may extend or stop a cycle to manage it; adding products or restarting will not fix the dosage.
The LG chart links Sud to foam control. Recovery time depends on the model family and should not be applied as a fixed wait time for every washer.
During the alert
If the machine is still running its routine and there is no leak, let it complete the recovery indicated in the manual. Do not add detergent or use a household product to neutralize the foam. Also do not open a door held by water or motion.
If water appears outside, stop use and address the leak first, shutting off the water supply if you can do so without coming into contact with water near electrical connections. An AE alert or water on the floor changes the priority.
Prevent it from happening again on the next load
Check that the detergent is compatible with the machine and measure the dose according to the load, soil level, and water hardness. A more concentrated formula needs a different amount. Residue from previous washes can also create foam even without adding new product.
To adjust usage, see dosage and excess foam. If the water does not drain, follow the OE drain check, without assuming the problem is all due to detergent.
Request service if Sud continues after the authorized recovery and usage correction, especially if it is accompanied by a drainage failure.