Bosch Washer Error Code d:18

Error code d:18 means the motor control unit has detected a peak voltage level that is too high during operation. This points to a fault in the motor control system. The washer stops operation to protect the motor and control electronics from damage caused by the overvoltage condition.

A power reset may temporarily clear the code, but d:18 is a hardware-level fault tied to an actual overvoltage event in the motor control circuit. If the underlying cause, typically a faulty motor control board, is not repaired, the error will return as soon as the washer attempts to operate the motor again.

If the repair requires a motor control board replacement, parts and labor typically range from $150 to $400 depending on the specific model and local labor rates. If the fault is caused by a wiring or connection issue, the cost will be lower since no major parts are needed. Getting a diagnostic assessment from a qualified technician will give you a more precise estimate for your situation.

The recommended diagnostic step is to run test program P4, which evaluates the motor control system under controlled conditions. If the test confirms the fault, the motor control unit needs to be replaced. Before replacing any parts, also verify that the household power supply voltage is stable and that all wiring harness connections to the motor control board are secure.

You should not continue running the washer while d:18 is active. The error indicates a fault in the motor control system involving abnormal voltage levels, which can cause further damage to the motor or control electronics if the machine is forced to operate. Leave the washer powered off until the fault is diagnosed and repaired.