Bosch documents E33 as excessive foam detection in compatible washing machines. The first check is the detergent and dosage, with the E-Nr confirmed.
Adjust to the actual wash
The manufacturer documentation points to reducing the dosage, especially with soft water or lightly soiled laundry. Also check the product concentration and the amount of clothing: do not use a full-load measure for every wash.
Count all products that may come with the laundry, including additives and pre-treatments. If the warning appeared after changing detergent, compare the chart on the new package instead of keeping the previous dosage.
Cycle recovery
Observe whether the machine performs extra rinses and let the manual cycle finish when there are no leaks. Do not add anti-foam mixtures or any other detergent to complete the program. To adjust future loads, consult dosage by load, soil level, and water hardness.
If E33 repeats with the dosage corrected or is accompanied by retained water, report both conditions to service. A third-party list that calls E33 a pressure switch failure does not replace the interpretation in your platform's manual.
Note the product and amount before changing them: this helps assess whether the adjustment changes how often the warning recurs.