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Error code reference

Bosch Dishwasher Error Code E:28

Aqua sensor doesn't run during wash cycle; error code won't show during wash cycle

Bosch codesBosch dishwasher codes
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What the E:28 error code actually means

Your Bosch dishwasher's E:28 code means a water-monitoring sensor inside the machine stopped working during the wash cycle. This sensor helps the dishwasher decide how hard it needs to clean, so when it fails, the machine flags the problem. You may need to run a special test mode on the dishwasher to see this error, since it does not appear on the display during normal washing.

Diagnostic procedure

The full E:28 procedure

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1
First diagnostic step
Run test program to check error codes. Check continuity between aqua sensor and power module. Make sure aqua sensor is clean where it enters the sump. If connections are good and sensor is clean or missing, replace aqua sensor.
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Most common causes of E:28

Ranked by how often they cause this code
  1. 1Dirty or contaminated aqua sensor
  2. 2Faulty wiring harness
  3. 3Faulty aqua sensor
  4. 4Missing aqua sensor

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Questions people ask about E:28

What does E:28 mean on a Bosch dishwasher?
E:28 on a Bosch dishwasher means the aqua sensor did not operate during the wash cycle. The aqua sensor monitors water clarity inside the sump to help the machine optimize cleaning. This code does not appear on the display during the wash cycle itself and is only revealed when a test program is run to retrieve stored fault codes. Causes include a dirty sensor, a wiring harness fault, or a sensor that is faulty or missing.
Will resetting my Bosch dishwasher clear the E:28 error?
A reset may temporarily clear the displayed fault, but E:28 will return if the underlying cause is not corrected. Because this code is stored and retrieved through the test program rather than shown live during the wash cycle, the fault condition in the sensor or wiring must be resolved for the error to stay gone. Cleaning the sensor or repairing the harness is necessary for a lasting fix.
How much does it cost to repair a Bosch dishwasher E:28 error?
If the fix is simply cleaning the aqua sensor, the cost is minimal, typically just your time. If the wiring harness needs repair or replacement, expect parts and labor costs in the range of $75 to $200 depending on the extent of the damage. Replacing the aqua sensor itself generally runs $50 to $150 for the part, with additional labor costs if a technician performs the repair.
How do I fix the E:28 error on a Bosch dishwasher?
Start by running the dishwasher's test program to confirm the E:28 fault. Next, locate the aqua sensor where it seats into the sump and clean any grease, scale, or debris from its surface. Then check for continuity between the aqua sensor connector and the power module to rule out a wiring harness fault. If the harness is good and the sensor is clean but the error persists, or if the sensor is missing, replace the aqua sensor.
Is it safe to keep using my dishwasher with an E:28 error?
An E:28 fault means the dishwasher is running without proper input from the aqua sensor, so it cannot optimize the wash cycle based on water clarity. The machine may still complete cycles, but cleaning performance could be reduced. While E:28 is not typically a water-leak or electrical safety hazard, it is advisable to diagnose and correct the fault to ensure the dishwasher is operating correctly.

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