Bosch Washer Error Code 42

Error code 42 on a Bosch washer means the control board detected an uncontrolled run-up of the drum motor, and has identified the cause as a broken Triac on the main control board. The Triac is the semiconductor component responsible for switching and regulating power to the motor. When it fails, the motor can spin erratically or without command, so the washer shuts down to prevent damage or injury. This error almost always requires control board inspection or replacement.

No, you should not continue using the washer while error code 42 is active. An uncontrolled motor run-up means the drum could spin without proper regulation, which can cause mechanical damage to internal components and creates a potential safety hazard. The washer should remain out of service until the control board has been inspected and repaired or replaced.

In most cases, yes, replacing the main control board resolves error code 42 because the failed Triac is integrated into that board. However, before installing a new board, it is important to inspect the drum motor and wiring harness for any shorts or damage that caused the original Triac failure. Replacing the board without addressing an underlying motor fault can result in the new board failing as well.

Yes, you can attempt a reset by activating the washer's test mode, which is the recommended first diagnostic step. However, if the underlying Triac or control board failure is not addressed, the error will return immediately or very quickly. A reset alone will not fix the root cause, but it is a useful starting point to confirm the fault is active and repeatable.

Repair costs depend on what component has failed. If only the control board needs replacement, parts typically range from $150 to $400 depending on the model, with labor adding $100 to $200 if a technician is hired. If the drum motor has also been damaged, total repair costs can be higher. Getting a diagnostic assessment before committing to repairs is advisable, especially on older machines.