Ryobi controller shows E10 and the generator will not start in AUTO mode.

Safety first: Confirm that utility power is present and the home is not relying on the generator. Keep the generator in OFF while inspecting safety circuits.

• Check emergency stop button: Locate the red emergency stop (E‑stop) button on the Ryobi standby generator enclosure. If it is pressed in, twist or pull it according to the label to reset it.
• Inspect E‑stop switch and wiring: Remove the panel behind the E‑stop. Check that the switch terminals are tight and wires are not broken. Look for moisture or corrosion.
• Test switch continuity: With power off and battery disconnected, use a multimeter to verify that the E‑stop switch changes state (open/closed) when pressed and released. Replace the switch if it does not operate correctly.
• Clear code and test: Reconnect the battery, clear E10, and attempt a manual start. If E10 persists with a known good switch, the controller input circuit may be faulty and should be evaluated by a technician.