Controller displays “Underfrequency” or “Low Frequency”; lights flicker and motors sound sluggish when on generator power.

Safety first: Turn generator OFF, open main breaker, and disconnect battery negative before inspection.

• Reduce load: Turn off nonessential loads and large motor loads. Restart the generator and see if frequency stabilizes near 60 Hz.
• Check fuel supply: Ensure gas shutoff valves are fully open. For LP, verify tank level and that regulators are not frozen. For NG, confirm adequate supply and that inlet pressure meets Kohler specs.
• Air intake and exhaust: Inspect and replace a dirty air filter. Check that exhaust is not blocked by nests, debris, or snow.
• Governor linkage: Inspect the mechanical governor linkage for binding or loose connections. Lubricate pivot points lightly if corroded.
• Measure frequency: With a qualified person, run the unit with no load and measure frequency. If it remains low, adjust the governor per the Kohler service manual or have the governor module evaluated.

Persistent underfrequency under light load suggests a governor or engine performance issue that should be addressed by a professional.