LG Dishwasher Error Code AC

The AC code on an LG dishwasher indicates an inverter PBA communication error. The main control board sent signals to the inverter PBA, which controls the wash motor, but received no response for 3 seconds. The dishwasher attempted this sequence three times, shutting the relay off for 3 minutes between each attempt, before displaying the code.

No, the dishwasher will not operate normally when the AC code is active, as the communication failure prevents proper motor control. Attempting to run cycles in this condition is not recommended, since the wash motor may not function correctly. Address the underlying cause before resuming use.

Repair costs vary depending on the root cause. If the fix is simply reseating a loose connector, the cost may only be a service call fee, typically in the range of $75 to $150. If the inverter PBA or main PBA needs to be replaced, parts alone can range from $100 to $300 or more depending on the model, with labor adding to the total. Getting a diagnostic estimate from a technician before committing to board replacement is advisable.

The first step is to check the communication wiring harness between the main PBA and the inverter PBA, as a loose or corroded connector is the most common cause. If the connectors are secure and the pins are clean, the fault likely lies with one of the two boards, which typically requires component-level diagnosis or board replacement. Board replacement is manageable for experienced DIYers who are comfortable working with appliance electronics, but if you are unsure, a qualified technician is recommended.

A power reset may temporarily clear the code if the fault was caused by a momentary communication glitch, but the code will return if there is an underlying hardware problem. To perform a reset, disconnect the dishwasher from power for several minutes and then restore power. If the AC code reappears after the reset and a wash cycle attempt, a physical inspection of the wiring and boards is necessary.