What to check yourself
Step 1. Check the garbage disposal knockout plug
Put this first because it catches a whole category of people: if the dishwasher was installed or the disposal replaced recently, and the machine has never drained properly since, the plug is almost certainly still in place. New disposals ship with a solid knockout in the dishwasher inlet, and it has to be punched out during installation. Miss it and the drain hose is connected to a sealed hole.
Step 2. Check the drain hose has a high loop
The hose must rise up under the counter before it drops to the drain, or the sink drains back into the dishwasher and the machine never reads as empty. Missing high loops are one of the most common installation faults in American kitchens.
Step 3. Scoop the standing water out
Use a cup and then a towel. You need the tub empty to reach anything, and starting another cycle to drain it just adds more water.
Step 4. Check the hose for kinks where it leaves the machine
The tightest bend is usually right behind the appliance, where the hose has been squashed when the machine was pushed back into its slot. Pull the machine out and look at the whole run to the sink cabinet.
Step 5. Clear the sink trap or the air gap
If the hose runs into a trap or an air gap on the countertop, both silt up with grease. Take the air gap cap off and clean the chamber. A blocked air gap looks exactly like a broken dishwasher.
When to call a technician
If the hose is clear all the way to the sink, the plug is out, the loop is right, and the machine still holds water. At that point the fault is the pump or the control side of it, and that is E23 territory rather than a blockage.
What the repair costs
| Repair | Part only | Fitted by a technician |
|---|---|---|
| Punching out the disposal plug or clearing the hose | - | Free |
| Plumber refitting the drain line with a high loop | - | $100 to $250 |
| Drain pump replacement | $20 to $100 | $100 to $400 |
A new machine of the same class runs $500 to $1,500. Once a quote passes about a third of that on an older appliance, the repair stops making sense.
Codes people confuse this with
Questions people ask
- It is a brand new dishwasher and it has never drained. Why?
- Nine times out of ten it is the knockout plug in the garbage disposal, which has to be punched out when the dishwasher is connected. It is a two minute job with a screwdriver and a hammer, and it is missed constantly.
- What is the difference between E24 and E22?
- E22 points at the filter inside the machine, which you can lift out and rinse in a minute. E24 points past it, at the hose, the trap or the disposal connection. If you have just cleaned the filter and still get E24, stop cleaning the filter and go look under the sink.
Which machines this applies to
Applies to
All Bosch dishwashers. Machines with newer electronics show E6103 for the same fault.
Last checked
2026-08-03