E31 Moderate Hard — consider a tech
Bosch Dishwasher E31 — Turbidity sensor fault
Bosch Dishwasher · Error code E31
What E31 Means
The optical turbidity sensor (which measures how dirty the wash water is, used by Auto/Eco programs) is out of range or has failed.
Symptoms
- Auto program errors or won't run
- Cycle defaults to longer fixed time
- E31 with otherwise normal operation
Common Causes
1
Soiled sensor optics
Limescale or grease coating the optical window.
2
Failed turbidity sensor
LED or photodiode in sensor has failed.
3
Sensor harness fault
Broken or disconnected harness to the sensor.
4
Control board input fault
Rare PCB-side input failure.
How to Fix It
- Run a hot Rinse cycle with a cup of white vinegar in the tub to clean optics.
- If still failing, remove the dishwasher and access the sump from below.
- Disconnect the turbidity sensor and clean the optical lens with a soft cloth.
- Reseat the harness connector.
- If the error persists after cleaning, replace the turbidity sensor.
Parts You May Need
If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.
More Bosch Dishwasher Codes
Verified against manufacturer documentation: bosch-home.com
Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician.