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Error code reference

Bosch Dishwasher Error Code E:26

Error code won't show during wash cycle; caused by faulty water switch harness or faulty water switch/water…

Bosch codesBosch dishwasher codes

Error code won't show during wash cycle; caused by faulty water switch harness or faulty water switch/water switch motor.

First step from the service manual

Run test program to check error codes. Check continuity between water switch and power module. Measure voltage to water switch (if ≈ 120 VAC, replace water switch or water switch motor; if not, replace power module).

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

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What E:26 means on a Bosch dishwasher

Bosch dishwasher error code E:26 is a water switch fault that does not display during an active wash cycle. Instead, it appears only when the dishwasher is placed into a test or diagnostic program, making it easy to overlook during routine troubleshooting. The water switch is a flow-sensing component that communicates with the power module (the main control board) to confirm that water movement and fill levels are within expected parameters. When this communication fails or the switch does not respond correctly, the control registers an E:26 fault.

The fault traces back to one of three components: the wiring harness connecting the water switch to the power module, the water switch itself, or the water switch motor. A broken, corroded, or open-circuit harness will interrupt the signal path between the switch and the control board. If the harness checks out and continuity is confirmed, the next step is to measure the voltage supplied to the water switch. Approximately 120 VAC at the switch terminals indicates the power module is functioning correctly and sending the proper supply voltage, which points to a failed water switch or water switch motor as the root cause.

If the voltage at the water switch terminals reads significantly below 120 VAC or is absent entirely, the power module itself is likely failing to supply the correct output and should be replaced. This two-step voltage check is the key diagnostic branch: it separates a failed output device (water switch or motor) from a failed control component (power module), preventing unnecessary parts replacement.

Source: manufacturer service documentation.

Common causes of E:26

  1. 01

    Faulty water switch or water switch motor

    Part replacement

    If 120 VAC is confirmed at the water switch terminals, the switch or its integrated motor has failed internally and is not responding to the control signal. Replacing the water switch or water switch motor resolves the fault in this scenario.

  2. 02

    Faulty water switch wiring harness

    Part replacement

    A broken, corroded, or open-circuit harness between the water switch and the power module interrupts the signal path and triggers E:26. Continuity testing across the harness will reveal any open or high-resistance connections.

  3. 03

    Faulty power module

    Part replacement

    If voltage measured at the water switch terminals is not approximately 120 VAC and the harness passes continuity testing, the power module is likely not delivering the correct output voltage. Replacing the power module is the recommended correction in this case.

  4. 04

    Corroded or loose connector pins

    Wiring / connection

    Connector pins at either end of the water switch harness can corrode or back out of their housing, creating intermittent open circuits that register as a switch fault. Inspect and reseat all connectors along the harness before condemning the switch or board.

See the test procedure for each cause

Frequently asked questions about E:26

What does E:26 mean on a Bosch dishwasher?
E:26 on a Bosch dishwasher indicates a fault with the water switch circuit. This code only appears during a diagnostic test program, not during a normal wash cycle. The cause is either a faulty water switch harness, a failed water switch, a failed water switch motor, or a failing power module. A voltage measurement at the water switch terminals is the key test to determine which component is at fault.
Can I fix Bosch E:26 myself, or do I need a technician?
Diagnosing E:26 requires running a test program, performing continuity checks on the wiring harness, and measuring 120 VAC at live terminals, all tasks that carry an electrical shock risk and require a multimeter and some familiarity with appliance wiring. Knowledgeable DIYers comfortable working around line voltage can follow the diagnostic steps, but those unfamiliar with electrical testing should hire a qualified technician. Replacing the water switch or harness is relatively straightforward once the faulty component is confirmed.
Will resetting my Bosch dishwasher clear the E:26 error?
A power reset may temporarily clear the E:26 code from the display, but it will not resolve the underlying hardware fault. Because this code only surfaces during a diagnostic test program, you may not see it return immediately after a reset. The water switch circuit problem will persist until the faulty harness, water switch, water switch motor, or power module is actually repaired or replaced.
Is it safe to keep using my dishwasher with an E:26 error?
Since E:26 does not display during a normal wash cycle, the dishwasher may continue to run, but the water switch fault means the control board may not be receiving accurate information about water flow or fill status. Running the appliance with a compromised water monitoring circuit carries a risk of improper fill levels or undetected water-related issues. It is best to diagnose and repair the fault before continued regular use.
How much does it cost to repair a Bosch dishwasher E:26 error?
Repair cost depends on which component is at fault. A replacement wiring harness is typically the least expensive fix, while a new water switch or water switch motor generally falls in a moderate parts price range. Replacing the power module is usually the most costly repair. Adding professional labor, total repair costs can range from around $100 to $350 or more depending on parts pricing and local labor rates.

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