Fault Code E121: INV Power Supply Low-Voltage Error.
Fault: INV Power Supply Low-Voltage Error.
When an error has occurred, a red LED on the timer setting panel turns on and an error code is displayed on the LED display. The panel does not turn to the display sleep mode while the error code is shown. After a component is replaced or the inspection is completed, turn the breaker on/off several times to confirm the error does not re-occur.