Bosch Dishwasher Error E09: Water Heating Fault
Appears when the heating element or its temperature sensor is not working correctly, so the dishwasher fails to reach the program temperature.
Common symptoms:
- Dishes come out cold with greasy residue
- Cycle takes much longer than usual
- E09 code or heating icon flashing
Probable causes:
The flow-through heater loses efficiency or fails internally and no longer heats the water passing through it.
The sensor reports incorrectly to the control board, which interprets the temperature as not rising and cuts heating as a safety measure.
The relay or triac that switches the heater has failed and does not supply current even when the cycle calls for it.
Safe Inspection Checklist (Check off when completed):
Cancel the cycle, unplug the dishwasher for 2 minutes, then restart with a short program to see if the error reappears from the start.
If you live in a hard-water area, run an empty high-temperature cycle with a dedicated descaler to remove limescale buildup on the heater.
Poor filling caused by dirty filters can trigger false heating warnings; clean the lower sump filters before ruling out the fault.
If E09 keeps appearing after cleaning filters and descaling, the heater or NTC sensor is damaged and needs technician replacement, as it is part of a sealed assembly.