Lifan standby generator cranks but does not start and the controller shows E03.

Safety first: Turn the generator OFF and isolate from utility power. Wear eye protection when working around batteries.

• Inspect battery connections: Check the positive and negative terminals on the Lifan starting battery. Clean any white/green corrosion with a baking soda and water solution, then tighten the clamps securely.
• Measure battery voltage: With a multimeter, measure across the battery posts. A healthy fully charged 12 V battery should read about 12.6–12.8 V with the engine off. If below 12.0 V, charge the battery with an external charger.
• Load test the battery: If available, use a battery load tester. If voltage drops excessively under load, replace the starting battery with one that meets Lifan’s cold cranking amp (CCA) specification.
• Check built-in charger: With AC utility present and generator off, measure voltage at the battery. It should be around 13.2–13.8 V if the Lifan battery charger module is working. If it remains at static battery voltage, inspect the charger fuse and wiring. Replace the battery charger module if no output is present.
• Clear code and test: After correcting battery and charger issues, reconnect everything, clear the E03 by cycling controller power, and attempt a manual start.