My bosch dishwasher won't drain

That normally signifies a leak. Under the machine there is a plastic pan with a sensor in it. However Bosch have a different idea.

https://www.google.com/search?q=Bosch+Series+6+dishwasher+Tap+error+symbol

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Check the "P trap" where the drain hose connects under the sink. It may be partially blocked allowing water to syphon back into the machine or preventing it from pumping properly after the second or third pump out.

Clean the drain filter in the bottom of the washer

Have you tried canceling the cycle? To cancel, turn the on/off switch to on, then press and hold for three seconds the two buttons labeled "Cancel Drain". Keep the door closed for the next minute so that the dishwasher can complete the cycle. During this time the pump will remove any water from the washer. Also you will notice that Bosch dishwashers always leave a little water in the system to keep the seals from drying out and going bad.
Hope this helps

see this causes and fix it. God bless you
Belt, Water Pump Although few dishwashers have a water pump belt, if the dishwasher won't drain there might be a worn or broken water pump belt. After removing the lower kick panel the motor can be seen in the front, the water pump belt is on the bottom of the motor.

Drain Pump If the dishwasher won't drain, the drain pump might be defective. Test the pump motor with an Ohm meter. Drain pumps are not repairable, if it's defective it will need to be replaced.

Drain Impeller The drain impeller is attached to the pump and pushes the water out of the dishwasher, through the drain tube and into the garbage disposer or drain line. If the dishwasher won't drain, the drain impeller might be broken or worn out. Replace both the impeller and seal at the same time.

Drain Solenoid Kit If the dishwasher won't drain, the drain solenoid kit might need to be replaced. The drain solenoid is an actuator that opens a flap to allow the water to drain.
Drain Valve The drain valve can get clogged with debris and should be cleaned out if the dishwasher won't drain. If it seems clear of debris but won't actuate, it will need to be replaced. The drain valve is not repairable.
Pump and Motor Assembly If the dishwasher won't drain, the pump and motor assembly might be defective. If the motor runs during the drain cycle, check for a blockage in the drain line. If the motor won't run during the drain cycle or if it just hums when it should be running, the pump and motor assembly might need to be replaced.

Clogged or Improperly Installed Garbage Disposer If the dishwasher won't drain and the garbage disposer was installed recently, the installer might have forgotten to knock out the drain plug from this disposer. All garbage disposers are sold with a solid plug in the drain tube for situations where a dishwasher isn't connected. However, if the dishwasher is connected, the plug will need to be removed. If the disposer wasn't replaced recently, remove the dishwasher drain hose from the disposer and clean out both the fitting on the disposer and the end of the drain hose. These are the most common places to find an obstruction if the dishwasher won't drain.

Drain Hose If the dishwasher won't drain the drain hose might be clogged. Remove the drain hose from both the dishwasher and the sink drain to clean it out. The most common place for an obstruction is at the garbage disposer.

Check Valve If the dishwasher won't drain the check valve might be stuck closed. The check valve is a small plastic device which prevents water from returning to the dishwasher after it has drained. If the valve gets stuck closed, it will prevent the water from draining. The check valve is the device that the drain hose is attached to on the dishwasher
Check Ball If the dishwasher won't drain the check ball might be stuck. The check ball is a small plastic ball in the check valve which prevents water from returning to the dishwasher after it has drained. If the ball gets stuck, it will prevent the water from draining also. The check valve is the device that the drain hose is attached to on the dishwasher.

I quote same wrong from other user:

Question: Model dishwasher is Bosch Exxcell SMS50E02
It stopped before the end of a cycle with the error code E:25 and the "check water" light came on
I mopped out all the residual water out of the bottom and then ran a rinse cycle, which after several trials I got to work and then it stopped at the end again with the same error code and water in the bottom as before.

Answer:
I assume by in the bottom you mean inside the dishwasher and not in the base.As long as there is no debris in the sump area and the hoses are clear it appears you have a bad drain pump.

Hope helps.

ensure filter in bottom of machine is not blocked. if clear
suspect blocked pipe or defective evacuation pump.

i hope this was helpful

Im really not all that familiar with the bosch unit, but a few things i would ck. when you cancel a cycle (it should drain the water) is it humming??? does it sound as if it even trickling into the sink discharge?? do you have a disposer under your sink that this unit drains into, if so remove the clamp and look for possible obstructions right there.Honestly passed this ill have to defer to someone else sorry and good luck

Hello Mimhoff it depends on how much water is down there. The sump area always has a little water in it to prevent the circulation pump seals from sticking. Usually around 1 to 2 inches. If there is more than that, check the slots at the bottom of the sump on the left side for being clogged and check the end of the drain hose to make sure it is clear. If you are getting a moldy/odor from the dishwasher, try running Dishwasher Magic or Tang thru the dishwasher. This will remove any build up of food or detergent from the dishwasher. If you are running the dishwasher every few days and just scraping your dishes, then either leave the door ajar or run the rinse & hold cycle to help keep the odor down. Bosch doesn't reccommend running bleach thru the dishwasher as this can cause damage to the rubber seals. However 2 tablespoons of bleach once a year won't hurt.

have you removed the filter? if it gets clogged the dishwasher wont drain. other wise is sounds like a faulty drain pump