What E28 means on your Bosch dishwasher
Error code E28 is related to E07 but specifically indicates a calibration fault with the AquaSensor rather than a complete failure. The sensor’s baseline readings have drifted outside the acceptable range, meaning it can’t accurately distinguish between clean and dirty water. This can happen gradually as the sensor ages or accumulates deposits.
Symptoms
- Cycles end too early — the sensor thinks the water is clean when it isn’t
- Or cycles run excessively long — the sensor never registers the water as clean enough
- Inconsistent wash results between loads
Common causes
- Mineral scale on sensor — hard water gradually coats the optical window
- Sensor aging — the infrared components degrade, shifting baseline readings
- Control board calibration data corruption — power surges can corrupt stored calibration values
Troubleshooting steps you can try
- Deep clean the sensor — remove filters and clean the AquaSensor lens with vinegar-soaked cloth.
- Run a calibration cycle — some Bosch models allow sensor recalibration through the diagnostic mode. Consult your model’s service manual for the specific key combination.
- Power reset — a full power cycle may clear corrupted calibration data.
When to call a technician
If cleaning and resetting don’t resolve E28, a technician can run the factory calibration procedure or replace the sensor. Like E07, this is a low-priority code — the dishwasher will still clean, just not optimally. Codes may vary by model generation and series.
Need help? Schedule Bosch Dishwasher repair with a certified technician, or contact our team for a free diagnosis consultation.
