Bosch Dishwasher Error Code Er:21

Er:21 means the dishwasher has detected excess foam inside the wash tub. The machine's sensors identified abnormal sudsing conditions, which can interfere with water circulation and fill levels. This error is almost always caused by using the wrong detergent or using too much of the correct detergent. It is not typically a sign of a mechanical failure.

Running the machine with significant foam present is not recommended, as excess suds can impair the circulation pump and affect wash performance. You should address the detergent issue and clear any visible foam before resuming a full wash cycle. The error is a protective alert, and resolving the underlying cause quickly prevents any risk of further problems.

In most cases, Er:21 requires no parts and no repair cost beyond the correct detergent. If a service technician visit is needed to diagnose or clear a persistent fault, expect to pay in the range of $75 to $150 for a service call depending on your location. Part replacement is rarely necessary for this specific error code.

Start by verifying that you are using a detergent specifically designed for automatic dishwashers and that the dispenser is not overfilled. Remove any standing foam from the tub using a cloth, then run one or two empty rinse cycles to flush out residual suds. Once the foam is cleared and the correct detergent dose is confirmed, the machine should resume normal operation.

A reset may clear the fault code from the display, but if the underlying foam condition is not resolved, the error will return in the next cycle. It is important to identify and correct the detergent type or dosing issue before simply resetting the machine. Flush the tub with rinse-only cycles after correcting the detergent situation to ensure all residual suds are gone.