Controller shows E04 and the generator will not crank.

Safety first: Confirm that it is safe to restart the generator and that no maintenance is being performed.

• Check emergency stop button: Locate the red emergency stop (E-STOP) on the generator enclosure. If it is pressed in, twist or pull it to release (per label instructions). Inspect for physical damage.
• Inspect remote stop wiring: If your Hyundai Power standby generator is connected to a remote stop or fire alarm circuit, verify that the remote device is not commanding a stop. Check the low-voltage wiring for breaks or loose terminals at the control module.
• Test E-STOP switch: With power off, disconnect the E-STOP switch from the harness and test continuity with a multimeter. It should be closed (or open, depending on design) when released and change state when pressed. Replace the switch if it does not change state reliably.
• Controller reset: After correcting the stop condition, cycle the controller power (OFF then AUTO) to clear E04. If the code persists with the E-STOP circuit verified, the control module input may be faulty and require replacement.