E24 on a Bosch dishwasher means one thing: it couldn’t drain, and there’s water sitting in the tub. Good news is that a clogged filter or a blocked air gap trips E24 just as often as an actual hardware failure, so two quick checks solve a lot of these before anyone has to come out. Here’s how to sort it.
What the code is telling you
Bosch throws E24 (or a blinking light pattern on older displayless models) when the control board runs the drain step and gets no confirmation the water left. That could be a clog anywhere in the drain path, a kinked hose, a blocked air gap or disposal, or a failed pump. It is not automatically a dead pump. Bosch has a separate code, E25, for a blocked or failed drain pump specifically. E24 is the broader “water didn’t leave” fault.
The usual culprits, most common first
Clogged filter. The number one cause by a wide margin. The cylindrical filter and flat mesh screen at the bottom of the tub pack up with food debris, water can’t move fast enough, and E24 trips.
Blocked air gap or kinked hose. The drain hose runs from the pump to a disposal or a drain stub, and it can kink behind the machine if the cabinet shifted. If you have a chrome or plastic air gap on the counter by the faucet, it clogs with grease over time and blocks the outflow. This one gets missed a lot.
Disposal knockout still in place. If the drain goes to a garbage disposal, there’s a plastic knockout plug that has to be removed during install. If the disposal was recently swapped and nobody knocked it out, nothing drains. Check this first if that’s your situation.
Drain pump failure. If the filter, hose, and air gap are all clear and E24 still comes back, the pump may be the issue, from wear or a bit of debris jamming the impeller. A hum or grind during the drain step is the tell.
Control board or wiring. Rare. A bad drain sensor or a wiring fault can throw a false E24. Last thing to look at, not the first.
The two safe checks
No tools needed for either.
Pull the bottom rack. Twist the cylindrical filter counterclockwise and lift it out, then lift the flat mesh screen underneath. Rinse both, scrub lightly if there’s buildup, and reinstall. Then check under the sink that the drain hose isn’t kinked or pinched against the cabinet. If you have an air gap, pop the cap and clear any gunk.
Run a short cycle and see if E24 clears. If it does, you’re done. If it comes back after the filter and hose are clean, stop there. Everything past that point means pulling the machine, testing pump voltage, and running Bosch’s diagnostic mode. Guessing wrong on a pump or a board costs more than a service call.
Where a tech takes it
When we get an E24 that survived the basics, we run the service diagnostic first. It logs fault history and tests components directly, including the drain pump, so we know whether the pump is getting power and trying to run or getting no signal at all. From there it’s verifying voltage at the pump, checking the impeller for an obstruction, inspecting the wiring harness, and testing the board outputs if everything else is clean. Diagnosis is fast. The repair depends on what actually failed.
When to call
Cleaned the filter, confirmed the hose is clear, checked the air gap, and E24 is still there? Call us. Pulling a Bosch the wrong way can tear the door seal or damage the float-switch wiring, and buying the wrong part is money down the drain. We work on Bosch dishwashers all over the Bay Area, usually same or next day. Schedule a visit at (925) 999-4095 and we’ll give you a straight answer on whether it’s worth fixing. The $75 diagnostic is credited to the repair.