Published 2025-01-09
An E15 on a Bosch dishwasher is the anti-flood system telling you it has found water where none should be: in the base pan under the tub. The machine will usually refuse to start and you may hear the drain pump running continuously. The code is a symptom, not a diagnosis, so the job is finding where the water came from before drying the pan and clearing the float.
What the E15 Float Switch Is Actually Reading
Every Bosch dishwasher has a shallow polystyrene base pan with a foam float and a microswitch. When even a small amount of water collects in that pan, the float rises and trips the switch, which the control reads as E15. That is why the fault often appears after a slow leak rather than a dramatic flood. The anti-flood logic then locks the cycle and runs the drain pump to protect the floor and cabinets.
Because the trigger is water in the pan, resetting the code by tipping the machine back only helps for a few minutes. Unless the leak source is found and fixed, the pan fills again and E15 returns on the next fill.
Where the Water Is Coming From
On the 300, 500, 800 Series and Benchmark units we service around Bridgehampton, the most common source is the small hose and seals inside the door, followed by a hairline split in the sump gasket or the heat exchanger. A perished spray-arm bearing seal or a cracked salt reservoir on hard-water installs can also seep slowly into the base.
We dry the pan completely, run a short cycle with the lower panel off, and watch exactly where the first bead of water appears. Chasing the origin this way is the difference between a lasting fix and a machine that throws E15 again in a fortnight.
Bosch Base-Water Fault Reference
| Code | What It Points To | Our First Checks |
|---|---|---|
| E15 | Water in the anti-flood base pan | Dry pan, pressure-test sump and door seals |
| E16 | Water intake with the fill valve closed | Inspect fill valve and aquastop for weeping |
| E24 | Drain restriction or blocked filter | Clear filter, check drain hose and pump |
| E22 | Filter or drain float fault | Clean fine filter, verify drain float free |
What We Replace and What We Do Not
The fix is almost never the float switch itself, which rarely fails. It is the leaking part upstream: a door seal, a sump gasket, a fill hose, or occasionally the heat exchanger. We only quote the part that is actually wetting the pan, so a healthy machine is not fitted with a control board it never needed.
Bosch showing E15 and a puddle under the door in Bridgehampton? Book a diagnosis and we will trace the leak, not just dry the pan.