Generator will not crank; controller shows E05 when a start is attempted.

Safety first: Ensure the generator is in OFF mode. Wear eye protection when working around batteries. Avoid sparks and open flames.

• Check battery connections: Open the access panel and locate the starting battery. Inspect the positive and negative terminals for corrosion or looseness. Clean corrosion with a mixture of baking soda and water, then tighten the terminals securely.
• Measure battery voltage: Using a digital multimeter, measure DC voltage across the battery posts. A healthy fully charged 12 V battery should read about 12.6–12.8 V. If it is below 12.0 V, the battery is significantly discharged.
• Charge or replace battery: Disconnect the battery and charge it with an external smart charger until full. If the battery will not hold a charge or is more than 3–5 years old, replace it with a WEN‑specified starting battery of the same group size and CCA rating.
• Check built‑in charger: With AC utility power present, measure voltage at the battery terminals; you should see a slight charging voltage (typically 13.2–13.6 V). If voltage does not rise when the charger is supposed to be active, test and replace the battery charger module as needed.
• Reset and test: Reconnect the battery, clear the E05 code, and attempt a manual start. If the code reappears with a known good battery, inspect the battery cables and ground connections to the frame and starter.