What the code means

LE means the leak sensor has found moisture where it shouldn't be, even if you can't see a leak.

When this happens, the dishwasher turns itself on and won't turn off while it tries to drain the water away.

Before you start

Unplug the dishwasher or switch off its breaker first. It keeps running on its own while the sensor is wet.
If you find a leak, turn off the water supply to the dishwasher.
Samsung says not to reset or clear the code before you look for the cause. Clearing it first leaves the cause in place, and the code can come back.

With the power off, look along the water supply hose, especially at both of its connections. If you find a leak, turn off the water supply and follow the steps for visible water below.
If the dishwasher was recently connected to a garbage disposal, check that the disposal's knockout cap was removed. If it is still in, water can reach the leak sensor.
Look for leftover detergent. Samsung says detergent is moist enough to set off the sensor and dries slowly. Make sure the dispenser isn't overfilled and there is no detergent outside it.
If the dishwasher was moved recently, give it time to dry.
Restore the power and check whether the code is still there.

Wipe up the water and run a new cycle to confirm it is a leak.
Check the water supply hose and the drain hose connection.
Check the door seal.
Use dishwasher detergent. Dish soap makes suds that can escape.
Check that the dishwasher is level.
Check that the cabinet screws aren't so tight they stretch the sides of the tub. Samsung says the opening should be twenty-two inches.
Clear food out of the spray nozzles.
On a Waterwall model, make sure nothing blocks the water reflector.
If the water supply hose is damaged, Samsung says hose damage isn't covered by service, and suggests a 3/8 inch stainless steel replacement.

Stop and call for service if any of these happen.

The code is still showing after the dishwasher has dried and the power is back on. Samsung says to request service.
You find a leak along the drain hose or a damaged rubber seal, or the leak continues after these steps. Samsung says to request service.

Source: Samsung: Dishwasher is displaying an error code; Samsung: Dishwasher is leaking or has a leakage error code.

Based on the manufacturer's support pages. Codes can differ by model, so your model's owner's manual comes first.