The E24 error code on a Bosch dishwasher means the machine can’t drain. It stopped mid-cycle and water is sitting in the tub. There are two homeowner checks worth doing first, because a clogged filter or blocked air gap causes E24 just as often as a hardware failure. If those don’t fix it, you need a tech.
What E24 Actually Means
Bosch uses E24 (sometimes displayed as a blinking light sequence on older models without a display) to signal a drain fault. The control board tried to drain and got no confirmation the water left. That could be a clog somewhere in the drain path, a kinked hose, a failed pump, or something downstream like a blocked garbage disposal knockout or air gap.
It doesn’t automatically mean a broken pump. (Bosch uses a separate code, E25, specifically for a blocked or failed drain pump. E24 is broader: anything preventing drainage.)
Most Likely Causes, in Order
Clogged filter assembly. The number one cause. The cylindrical filter and flat mesh screen at the bottom of the tub collect food debris, and if you haven’t cleaned them in a while, they pack up tight. Water sits on top, the pump can’t move it fast enough, and E24 trips.
Blocked drain hose or air gap. The drain hose runs from the pump to either a garbage disposal or a dedicated drain stub under the sink. It can kink behind the dishwasher if something shifted in the cabinet. If you have an air gap (the chrome or plastic cap on the countertop near the faucet), it can clog with grease and food over time and block the outflow path. A common E24 trigger that gets missed.
Garbage disposal knockout not removed. On installations where the drain runs to a disposal, there’s a plastic knockout plug in the disposal inlet that has to be removed during install. If it wasn’t, nothing drains. If the disposal was recently replaced, check this first.
Drain pump failure. If the filter is clean, the hose is clear, the air gap is fine, and E24 still comes back, the drain pump itself may be the problem. The pump can fail from wear, or a small piece of debris can jam the impeller. You might hear it: a humming or grinding noise during the drain cycle means the motor is trying but something is blocking it.
Control board or wiring issue. Rare. If the pump tests fine and everything else is clear, a faulty drain sensor or wiring fault can cause a false E24. Last thing to check, not the first.
Two Things to Check Yourself
The filter and air gap are homeowner-safe checks, no tools required.
Pull the bottom rack out. The cylindrical filter at the bottom of the tub twists out counterclockwise, no tools needed on most Bosch models. There’s a flat mesh screen underneath it. Rinse both under the faucet, scrub lightly if there’s buildup, and reinstall. Then check under the sink and confirm the drain hose isn’t kinked or pinched against the cabinet wall.
If you have an air gap, pop the cap off and clear any debris. Reassemble, run a short cycle, and see if E24 clears.
If it does, you’re done. If E24 comes back after the filter and hose check out clean, stop there. Everything past that point involves pulling the machine, testing pump voltage, and running Bosch’s diagnostic mode. That’s not homeowner work. Guessing wrong on a pump or control board costs more than a service call.
What a Tech Checks
When we see an E24 that didn’t clear after the basics, the first step is running a diagnostic cycle. Bosch has a service mode that logs fault history and tests individual components, including the drain pump. That tells us whether the pump is receiving power and trying to run, or whether it’s not getting a signal at all.
From there it’s usually: verify voltage at the pump, check the impeller for obstruction, and test the control board outputs if everything else checks out. A wiring harness inspection is part of it too, especially on machines a few years old. If the pump needs to come out, that requires pulling the dishwasher.
Diagnosis is fast. The repair depends on what’s actually wrong.
Call Us If the Basic Checks Don’t Fix It
If you’ve cleaned the filter, confirmed the hose is clear, checked the air gap, and E24 is still there, call a tech. Pump replacement and control board diagnosis aren’t jobs worth guessing on. Pulling a Bosch dishwasher the wrong way can damage the door seal or float switch wiring, and misdiagnosing the cause wastes money on parts you don’t need.
We work on Bosch regularly. If you’re in the Tri-Valley or East Bay, schedule at adriumservice.com. Same or next-day availability most days, and we’ll give you a straight answer on whether it’s worth fixing.