Bosch Dryer Error Code E:21

E:21 on a Bosch dryer means the control module has detected an incorrect checksum, indicating that its internal data or memory is corrupted or has failed a verification check. The dryer shuts down immediately when this fault is detected and cannot be restarted. This is a control board integrity error, not a sensor or mechanical fault. Replacing the control module is the required fix.

The correct fix for an E:21 error is to replace the faulty control module. This is not a fault that can be resolved through wiring checks, sensor testing, or resetting the unit. A qualified technician should source the correct replacement control board for your specific Bosch dryer model and install it. After replacement, the dryer should resume normal operation.

Repair costs for an E:21 error typically involve the price of a replacement control board plus labor. Control board parts for Bosch dryers generally range from $100 to $300 or more depending on the model, and professional labor charges typically add $80 to $200 depending on your location and service provider. Total repair costs commonly fall in the range of $180 to $500. Getting a service estimate before authorizing repair is advisable, especially on older units.

No, a standard reset or power cycle will not clear the E:21 error. Because the fault is caused by a corrupted or failed control module, the error will return immediately even after power is restored. The dryer is also locked out from restarting, so resetting has no effect on resolving this fault. The control board must be replaced.

The dryer will not operate when displaying E:21, so there is no immediate safety risk from continued use since the machine locks itself out. However, you should not attempt to bypass the lockout or force the dryer to run. Leave the dryer unpowered until the control board has been inspected and replaced by a technician.