Dishwasher holds water

if you dishwasher holds water that means the plumbing connections may be faulty. Most dishwashers are connected to the water supply with metal pipe fittings, and the leak could be at these fittings. If the fittings are threaded, tighten them with an adjustable wrench. If this doesn't work, chances are the threads are stripped or the fitting is cracked or otherwise damaged. In this case, replace the fitting.

Most dishwashers discharge used water through a pipe or a hose connected to the drain or garbage disposer under the kitchen sink. If the drain line is made of flexible hosing, it may have cracked from prolonged exposure to hot water. Examine the hose; if it's damaged, replace it. If the hose is leaking at its connections with the disposer or dishwasher, tighten the fittings or clamps at the connections, or replace the clamps. Also check for water leaks around inlet valves, drain valves, and anywhere you see flexible hoses and hose connections. Leaks at clamps can be stopped by tightening or replacing the clamps. Leaks in hoses can be eliminated by replacing the hoses.
also it may be due to faulty pump
Servicing the Water Pump

In most dishwashers, the water pump is located under the lower sprayer arm. This component pumps the water through the dishwasher. The pump has two impellers, top and bottom. These, as well as other components, can become clogged with food or detergent. Here's how to disassemble the pump:

Step 1: Remove the cap that holds the sprayer arm on.

Step 2: Remove the sprayer arm, the screen, the pump housing, a bolt, the upper impeller, the food disposer blade, a spacer plate, the impeller hood, a flat plate, an O-ring, and the lower impeller. Lay the parts out in order as you disassemble them so that you'll be able to reassemble them properly.

Step 3: Clean the parts thoroughly with a mild detergent solution. If any parts are worn, replace them with new ones made for the dishwasher.

Step 4: Replace any seals, such as the O-ring or other washers, with new ones.

Step 5: Reassemble the pump, keeping the parts in order.

To reach the water pump, remove the sprayer arm and screen and then the pump housing. Remove the bolt, and the pump components can be disassembled.

On some dishwashers, the lower impeller serves as a drain pump. This type of system usually has a reversible motor; machines with nonreversible motors have drain valves, as detailed previously. If your machine possesses this impeller pump system, and the water will not drain from the dishwasher, clean the lower pump impeller. This may solve the problem. Otherwise, call a professional service person.

Check the drain hose, check the net and the filter at the bottom of the machine, see if they are obstructed.
If you do not find any obstruction it may be a faulty pump, a faulty solenoid, or an internal problem with drain lines.

See this link here for a detailed explanation.