Bosch dishwasher error codes: most of them are water in the base, the drain, or a filter nobody has pulled.

The float switch in the base pan under the tub lifted — water collected under the dishwasher. The control shuts the inlet and runs the drain pump so the base cannot overflow; on an AquaStop model the tap symbol lights with it.

1. Turn the water supply off under the sink and switch the dishwasher's breaker off.
2. Pull the dishwasher out a few inches (the kick plate off first) and look for a wet floor, a drip at the inlet line, or a wet pump cover inside the tub — a spill from a tipped bowl, a cracked spray arm, or a pump cover left off after the filter was cleaned all land in the base.
3. Tilt the dishwasher back about 45° with a helper over a towel so the water in the base runs out the back, then set it level again. The float drops and the code clears on the next power-up.
4. A machine with no leak that still trips: the base pan is holding condensation from a cycle run with the door opened early, or the drain hose siphoned water back in — check the high loop.

Drain the base, fix the drip, reseat the pump cover and run a Quick wash. If the base fills again with the lines dry and the cover down, the water is coming from inside — a tub seal, a door gasket, the sump or a hose off the circulation pump. That is a service call; on a machine under warranty, a warranty call.

The drain pump ran and the water did not leave the tub — the hose is pinched, the drain it empties into is blocked, or the pump cover has lifted.

1. Under the sink: the drain hose is not kinked where it bends up into the high loop, and it is not crushed behind the dishwasher.
2. The disposal: a new disposal with its knockout plug still in takes no water; a disposal full of food backs up the hose. Run it with water for a minute.
3. The air gap on the counter, when there is one — pop the cap and clear the lint and food from inside it.
4. Inside the tub: the filter is out, the pump cover under it is clicked down (press until it clicks, not just laid in), and nothing is wedged in the pump impeller — a glass chip, a bone, a pit.
5. Hold Start three seconds to drain; if water stays in the tub, the drain itself is blocked — pour a bucket of water down the sink; if it backs up, the house drain is the problem.

Straighten the hose, clear the disposal, the air gap or the pump, click the cover down and run a Quick wash. A dishwasher that still prints E24 with a clear hose, an open drain and a clean pump has a drain pump that runs and moves nothing — a part.

The drain pump turned and found something in its way, or its cover is not seated so it cannot build pressure. Nearly always a thing in the pump.

1. Pull the bottom rack and the filter (turn the round filter a quarter turn and lift). Under it is the pump cover — press its tab and lift it out.
2. Reach into the pump opening with a flashlight on it: a broken glass, a toothpick, a label from a jar, a fruit pit. Turn the impeller by hand; it should turn freely with a slight resistance.
3. Put the cover back and press until it CLICKS — a cover laid in without the click is this code on the next cycle.
4. The drain hose and the disposal as under E24.

Clear the pump, click the cover down, refit the filter and run a Quick wash. An impeller that will not turn with the pump empty, or a pump that hums and never moves water, is the drain pump — a part, a service call.

Water is not getting through the filter fast enough — the fine filter, the coarse filter or the micro filter is packed with food, or something is sitting in the sump.

1. Pull the bottom rack and turn the round filter counterclockwise a quarter turn; lift the whole filter assembly out — the cylinder, the flat micro screen and the coarse cup come as one.
2. Rinse every part under the tap with a soft brush; grease and paper labels block the fine mesh even when it looks clean.
3. Look into the sump the filter sat in — pull out whatever is there.
4. Seat the filter and turn it clockwise until the arrows line up; a filter not locked lets debris into the pump.

Clean filters clear the code. Pull and rinse them every two to four weeks in normal use — it is the one maintenance a Bosch asks for.

The control drove the drain pump and read a motor that is not turning or a winding it does not believe — not a blockage, the pump itself.

1. The pump cover and the impeller as under E25 — a jammed impeller can print this instead.
2. Switch the breaker off for one full minute and run a Quick wash.

E23 that returns with the impeller clear is the drain pump or its wiring — a part, replaced from under the dishwasher. A service call.

The flow-through heater that warms the wash water is not heating, or the control measured a temperature it does not believe. The dishwasher may wash cold and never dry.

1. Switch the breaker off for one full minute and run a Quick wash. Feel the inside of the door at the end of the wash — a dishwasher that washed hot was heating.
2. Limescale: a hard-water house that has never used a descaler may read as a heater fault; see E12 below.

E09 that returns is the heater (built into the circulation pump housing on these models) or its relay on the control — a part, replaced from under the dishwasher. A service call.

The heater is coated in scale and the control sees it heating slowly. Hard water with no rinse aid and no descaler lands here after a year or two.

1. The rinse aid dispenser on the door is full — rinse aid is what keeps the scale from settling on everything.
2. White film on the glasses and the tub walls: that is the same scale.

Run an empty cycle on the hottest wash with a dishwasher descaler (citric acid works) in the bottom of the tub, then keep the rinse aid full. Two descaling runs in a row for a heavy coat. A heater that still trips with the tub clean is the heater — a part.

The control drove the wash pump — the one that sprays the arms — and read a winding or a motor that is not turning. The arms never move and the dishes come out as they went in.

1. Switch the breaker off for one full minute and start a Quick wash; listen for the hum of water hitting the door after the fill.

A circulation pump that never runs after a reset is the pump motor or its control — a part under the tub. A service call.

The wash pump tried to turn and could not — something has gone past the filter and into the pump, or the pump's rotor is stuck.

1. Pull the filter and look into the sump; the circulation pump draws from there, under the filter housing. Fish out whatever is there — a bit of glass, a cherry pit, a label.
2. The filter was locked in place (arrows lined up) the last time it was cleaned; a loose filter is how things reach the pump.
3. Switch the breaker off for one minute and run a Quick wash.

A clear sump and a locked filter settle most of them. A pump still jammed is opened from under the dishwasher — a technician's job, and a worn rotor is a part.

The turbidity sensor (Bosch's AquaSensor) that reads how dirty the wash water is answered with a reading the control does not believe. The dishwasher still washes; it just cannot judge the soil.

1. Pull the filter and wipe the small clear window in the sump floor beside the filter seat — grease over the sensor eye prints this.
2. Switch the breaker off for one minute and run a Quick wash.

A clean sensor window that still trips is the sensor or its wiring — a part under the tub, a service call. Dishes still wash meanwhile on a fixed-length cycle.

The control module found a fault inside its own circuits. Bosch publishes E01, E02 and E03 as technical faults with no home check.

1. Switch the breaker off for five full minutes, switch it on and start a Quick wash.
2. A storm or a flicker the night before: once is a power blip; twice is the board.

A control code that returns after a five-minute power cut is the control module — a part, behind the door panel. A service call.