Generator shuts down and displays E09 when large loads start (e.g., air conditioner)

Safety first: Open the generator main breaker and the building's transfer switch or main disconnect before inspection. Turn OFF the generator and disable auto-start.

• Reduce load: Identify and temporarily turn off high-demand loads (HVAC, electric ovens, water heaters). Attempt a manual run with only essential circuits. If E09 does not recur, your system is overloaded and needs load management or a larger generator.
• Inspect main breaker: Check the generator's main breaker for signs of overheating, burning, or mechanical damage. Cycle it OFF and ON several times. A breaker that feels loose or fails to latch may need replacement.
• Check for wiring faults: Have a qualified electrician inspect the transfer switch and load center for shorts, loose connections, or miswired circuits. Overcurrent can be caused by a shorted branch circuit.
• Measure current draw (electrician): Using a clamp meter, measure current on each phase during operation to ensure it is within the generator's rated output and reasonably balanced.
• Do not bypass protection: Never bypass or oversize the main breaker to stop E09; this can cause fire or equipment damage.