Bosch Dishwasher Error Code d:18

Error code d:18 on a Bosch dishwasher means the motor control system has detected a peak voltage that is too high during operation. This is a protective fault that stops the dishwasher to prevent damage to the motor or control electronics. The fault points to a faulty motor control board as the most likely cause. A built-in diagnostic test, P:04, is used to confirm the fault before replacing the board.

You should not continue operating the dishwasher while d:18 is active. The error indicates an abnormal voltage condition in the motor control circuit, and running the appliance in this state could cause further damage to the motor or control board. The dishwasher will typically stop operation automatically when this code is triggered, which is the intended protective behavior.

Repair costs depend on whether only the motor control board needs replacement or if additional components like the motor are also involved. Motor control board parts typically range from $80 to $250 depending on the specific Bosch model, and professional labor can add $100 to $200 on top of parts costs. Getting a diagnostic quote from a technician before committing to the repair is advisable, especially on older units.

The first step is running diagnostic test P:04, which is accessible through the dishwasher's service mode and requires familiarity with Bosch diagnostic procedures. If the test confirms a faulty motor control board, replacing it involves working with high-voltage components inside the appliance. Homeowners comfortable with appliance repair can attempt this, but if you are unsure about working with electrical components, a qualified technician is recommended.

A power reset may temporarily clear the d:18 code and allow the dishwasher to start again, but the underlying fault will cause the error to return. Because d:18 points to a hardware problem with the motor control board, the code will reappear until the faulty component is repaired or replaced. Resetting without addressing the root cause is not a reliable fix.