Error code reference

Bosch Dishwasher Error Code 8

Water supply error; overflow level reached due to valve not closing, valve senile, or component part failure.

Bosch codesBosch dishwasher codes

Water supply error; overflow level reached due to valve not closing, valve senile, or component part failure.

First step from the service manual

Firstly close water tap, then switch off the device for repair.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What 8 means on a Bosch dishwasher

Error code 8 on a Bosch dishwasher indicates the control board has detected a fault with the NTC (Negative Temperature Coefficient) thermistor, the sensor responsible for monitoring water temperature throughout the wash cycle. The control board reads resistance values from the NTC continuously; at room temperature (72°F), a functioning NTC should measure approximately 55 kΩ. When the board receives a resistance reading that falls outside the expected range, or gets no signal at all, it triggers error code 8 and halts the cycle to prevent heating errors or potential overheating.

For homeowners, the NTC is a small sensor mounted in the wash tub or on the heating circuit that tells the dishwasher how hot the water is. Without accurate temperature readings, the machine cannot properly control its heating element, meaning dishes may come out cold or the heater could run unchecked. The dishwasher shuts down as a protective measure when this sensor fails or loses its connection to the control board.

The fault can stem from a failed NTC sensor itself, damaged wiring between the sensor and the control board, corroded connectors, or in rarer cases a failed control board that cannot accurately read a functioning sensor. Diagnosis starts at the sensor with a multimeter resistance check before assuming any other component is at fault.

Source: manufacturer service documentation.

Common causes of 8

  1. 01

    Failed NTC thermistor

    Part replacement

    The NTC sensor itself has drifted out of spec or failed completely, producing a resistance reading that does not match the expected ~55 kΩ at 72°F. This is the most common cause of error code 8 and is confirmed with a multimeter resistance check directly at the sensor terminals.

  2. 02

    Damaged or broken wiring harness to NTC

    Part replacement

    The wire harness connecting the NTC to the control board can crack, corrode, or break, especially near connection points where the wiring flexes during door operation. A broken wire causes the control board to see an open circuit instead of a valid resistance reading.

  3. 03

    Corroded or loose NTC connector

    Wiring / connection

    Moisture inside the dishwasher can corrode the connector pins where the NTC plugs into the wiring harness, increasing resistance in the circuit or causing intermittent signal loss. Cleaning or re-seating the connector sometimes resolves the fault without replacing the sensor.

  4. 04

    Failed control board

    Part replacement

    If the NTC sensor and all wiring test within spec, the control board's input circuit for the temperature sensor may have failed and is misreading a valid signal. This is the least common cause and should only be considered after all other components have been verified.

See the test procedure for each cause

Frequently asked questions about 8

What does error code 8 mean on a Bosch dishwasher?
Error code 8 means the control board has detected a fault with the NTC temperature sensor, which monitors water temperature during the wash cycle. The board expects to read approximately 55 kΩ of resistance from the sensor at room temperature. When the reading is absent or out of range, the machine stops and displays code 8.
How do I fix error code 8 on a Bosch dishwasher?
Start by unplugging the dishwasher and locating the NTC sensor, which is typically mounted in the wash tub near the heating element. Disconnect the sensor and measure its resistance with a multimeter; at 72°F it should read approximately 55 kΩ. If the reading is far off or shows an open circuit, replace the NTC. If the sensor reads correctly, inspect the wiring harness and connector between the sensor and the control board for damage or corrosion.
Can I still use my Bosch dishwasher when error code 8 is showing?
Running the dishwasher with error code 8 active is not advisable. Without a functioning temperature sensor, the control board cannot regulate the heating element accurately, which means water may not reach proper sanitizing temperatures or, in a worst case, the heater could run longer than intended. Most Bosch units will not complete a cycle while this code is active anyway.
How much does it cost to fix error code 8 on a Bosch dishwasher?
An NTC temperature sensor for a Bosch dishwasher typically costs between $15 and $40 for the part, and replacing it is a relatively accessible repair requiring only basic tools and a multimeter. If a technician performs the repair, expect to add $80 to $150 in labor. If the fault turns out to be the control board rather than the sensor, board costs range from $100 to $300 or more, which may affect whether repair is worthwhile on an older unit.
How do I test the NTC sensor for error code 8 on a Bosch dishwasher?
Disconnect power to the dishwasher, then locate and unplug the NTC sensor connector. Set a multimeter to the resistance (ohms) setting and touch the probes to the two sensor terminals. At a room temperature of approximately 72°F, a good NTC should read close to 55 kΩ. A reading that is significantly higher, lower, or shows OL (open loop) confirms the sensor has failed and needs replacement.

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