Replacing the circulation pump cleared the error and restored function. I had earlier had to replace the hoses to the circulation pump and leak sensor because of repeated error 01 (water leak detected). Apparently, the leak was from both a hose damaged by hose clamps and a tiny progressive leak through the motor pump bearing. Unit was installed 6 years ago. You will need a small nut driver for the motor capacitor (3/16"?) and torx bits for the base that holds the motor.