Bosch Refrigerator Error Code E31

E31 indicates a defect in the icemaker tray temperature sensor or the water tank temperature sensor. These are NTC thermistors that the control board monitors to manage the ice-making cycle. The fault is confirmed by measuring sensor resistance, which should be approximately 10kΩ for the tray sensor and 5kΩ for the water tank sensor at 25°C. If either reading is significantly off or shows an open or short circuit, the sensor or its wiring is the source of the code.

The main refrigerator and freezer compartments typically continue operating normally while E31 is active, so food safety is generally not at immediate risk. However, the icemaker may stop producing ice or behave erratically until the sensor fault is resolved. It is best to address the repair promptly to prevent any secondary issues with the icemaker system.

A power reset may temporarily clear the E31 code from the display, but if the underlying sensor or wiring fault still exists, the code will return once the control board runs its diagnostic check again. A reset is useful for confirming whether the fault is intermittent, but it is not a substitute for diagnosing and correcting the actual sensor or wiring problem.

A knowledgeable DIYer can diagnose E31 by testing sensor resistance with a multimeter and inspecting the wiring harness and connectors for damage. If a connector is simply loose, reseating it may clear the code without parts. Replacing the faulty sensor is also a manageable repair for someone comfortable working with appliance electronics, but if the control board itself is suspected, professional service is advisable.

If the fix is a loose connector, there may be no parts cost at all. Replacing an icemaker tray or water tank sensor typically involves parts costs in the range of $20 to $80 depending on the specific sensor and source. If professional labor is needed, total repair costs including diagnosis and installation commonly fall in the range of $100 to $250.