Controller shows E06 and the generator will not start or shuts down shortly after starting.

Safety first: Turn the generator OFF and isolate it from automatic start (AUTO disabled). Wear eye protection when working around batteries.

• Inspect battery connections: Open the battery compartment on the Ryobi standby generator. Check that the positive and negative terminals are tight and free of corrosion. Clean corrosion with a mixture of baking soda and water, then rinse and dry. Re‑tighten terminals securely.
• Measure battery voltage: With a multimeter, measure DC voltage across the battery terminals. A healthy, fully charged 12 V battery should read around 12.6–12.8 V with the generator off. Below ~12.2 V indicates a low charge.
• Charge or replace battery: If voltage is low, charge the battery with an external smart charger rated for the battery type. If the battery fails to hold charge or is more than 3–5 years old, replace it with the exact capacity and type recommended by Ryobi.
• Check built‑in charger: With utility power present and the generator in standby, measure battery voltage again after several hours. If it does not rise, the internal battery charger or its fuse may be faulty and should be tested and replaced by a technician.
• Clear code and test: After restoring proper battery voltage, clear E06 and perform a manual start. If the code returns, have a professional check the charger circuit and controller.