Bosch Dishwasher Error Code 1

Error code 1 on a Bosch dishwasher signals a fault with the Aqua Sensor, also called the Sensotronic sensor. This optical sensor measures water clarity in the sump to help the dishwasher automatically adjust wash intensity and water use. When the control board detects an invalid or missing signal from this sensor, it triggers code 1 and may stop the cycle.

Running the dishwasher with code 1 active is not recommended. Without a functioning Aqua Sensor, the control board cannot regulate wash cycles based on water clarity, which can result in poor cleaning performance, excessive water use, or an incomplete cycle. On some Bosch models the dishwasher will halt mid-cycle when this fault is detected, making continued use impractical until the sensor issue is resolved.

A reset may temporarily clear the code, but it will return as soon as the control board polls the Aqua Sensor again during the next cycle. To clear code 1 permanently, the underlying sensor fault must be corrected by cleaning the sensor lens, repairing the wiring, or replacing the sensor. A reset alone is not a fix for this code.

Start by locating the Aqua Sensor in the sump area at the bottom of the dishwasher and cleaning its optical lens with a soft cloth and a mild descaler or white vinegar to remove grease and limescale buildup. If the code returns after cleaning, use a multimeter to check the sensor wiring harness for continuity and inspect the connector pins for corrosion. If the wiring is intact and the fault persists, the Aqua Sensor unit itself needs to be replaced, which is a moderate DIY repair requiring removal of the lower spray arm and sump cover.

If cleaning the sensor lens resolves the fault, there is no parts cost. A replacement Bosch Aqua Sensor unit typically costs between $20 and $60 depending on the specific model. If you hire a technician, expect an additional $80 to $150 in labor, bringing the total repair to roughly $100 to $210. The sensor replacement itself is accessible to confident DIYers with basic tools, which keeps costs lower if you do the work yourself.