Error code reference

Bosch Dishwasher Error Code #K

Apexx display

Bosch codesBosch dishwasher codes

Apexx display: NTC fault (short-circuited or open-circuited).

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What #K means on a Bosch dishwasher

Error code #K on a Bosch dishwasher with an Apexx display indicates the control board has detected an NTC (Negative Temperature Coefficient) thermistor fault. The NTC is a temperature sensor that changes its electrical resistance as temperature rises or falls. The control board monitors this resistance continuously, and code #K triggers when it reads either a short circuit (resistance near zero, indicating a shorted sensor or wiring) or an open circuit (infinite resistance, indicating a broken wire or failed sensor). Both conditions prevent the board from obtaining a valid temperature reading.

For homeowners, the NTC thermistor is the component that tells your dishwasher how hot the water is. Without accurate temperature data, the machine cannot properly control heating during the wash or drying cycle. Code #K means the dishwasher has either detected a broken connection to that sensor or the sensor itself has failed internally. The dishwasher may stop mid-cycle or refuse to start because it cannot safely manage water temperature without this input.

The fault is typically in the NTC sensor itself, its wiring harness, or the connector pins linking the sensor to the control board. Physical damage, corrosion, or heat exposure inside the dishwasher tub area are common contributors.

Source: manufacturer service documentation.

Common causes of #K

  1. 01

    Failed NTC thermistor

    Part replacement

    The NTC sensor itself has developed an internal short or open circuit, causing it to report an invalid resistance value. This is the most common cause of this code and requires replacing the sensor.

  2. 02

    Open circuit in NTC wiring harness

    Part replacement

    A broken or severed wire in the harness connecting the NTC thermistor to the control board produces an infinite resistance reading, triggering the open-circuit fault condition. Inspect the wiring along its entire run for breaks or burn marks.

  3. 03

    Corroded or damaged NTC connector

    Wiring / connection

    Corrosion, moisture intrusion, or a loose connector at the NTC sensor or control board end can create an intermittent or complete open circuit without the wire itself being broken. Cleaning or reseating the connector may resolve this without part replacement.

  4. 04

    Shorted NTC wiring harness

    Part replacement

    If two wires in the NTC circuit contact each other or a ground due to damaged insulation, the control board reads near-zero resistance and registers a short-circuit fault. Inspect the harness for chafing, pinch points, or melted insulation.

See the test procedure for each cause

Frequently asked questions about #K

What does error code #K mean on a Bosch dishwasher?
Code #K on a Bosch dishwasher with an Apexx display signals an NTC thermistor fault. The NTC is a temperature sensor, and this code means the control board detected either a short circuit or an open circuit in that sensor's circuit. The dishwasher cannot accurately read water temperature and will typically halt operation until the fault is resolved.
How do I fix error code #K on my Bosch dishwasher?
Start by disconnecting power to the dishwasher and locating the NTC thermistor, which is typically mounted in the sump or heating element area. Inspect the wiring harness and connectors for visible damage, corrosion, or loose pins and reseat any suspect connections. Use a multimeter to test the NTC sensor's resistance at room temperature, which should read several thousand ohms for a healthy sensor. If the sensor reads zero or infinite resistance, replace it. If the wiring and sensor both test correctly, the control board may need inspection by a technician.
Is it safe to keep using my Bosch dishwasher when error code #K is showing?
Running the dishwasher with an active #K code is not recommended. The NTC thermistor is how the machine monitors water temperature, and without valid temperature feedback the control board cannot regulate heating safely. Continued use risks inadequate sanitation if the water does not reach proper temperature, or overheating if the heating element runs without reliable sensor input. Stop using the appliance until the fault is diagnosed and repaired.
How much does it cost to repair error code #K on a Bosch dishwasher?
If the NTC thermistor itself has failed, the part typically costs between $15 and $50 depending on the model, and replacing it is a moderately accessible DIY repair for someone comfortable working with appliance wiring. If the issue is a damaged wiring harness, parts cost is similar but routing and securing new wiring takes more time. A professional repair visit adds $100 to $200 or more in labor. If the fault traces back to the control board, board replacement costs can reach $150 to $350 for parts alone, making professional diagnosis worthwhile before committing to that expense.
Can I reset error code #K on a Bosch dishwasher by cutting the power?
Cycling power or performing a reset may temporarily clear the #K code from the display, but the code will return as soon as the control board runs its diagnostic and detects the same NTC fault again. A power reset does not fix a failed sensor, broken wire, or corroded connector. Use the reset only to confirm whether the fault is intermittent or persistent, not as a substitute for diagnosing the underlying problem.

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