Liquid-cooled Kohler standby generator shuts down and displays “Low Coolant Level” or coolant level alarm.

Safety first: Turn the generator OFF, open the main breaker, disconnect battery negative, and allow the engine to cool completely. Never open the radiator cap on a hot engine.

• Check coolant reservoir: On liquid‑cooled Kohler units (e.g., 20RESC, 30RCL, 38RCLB), locate the coolant overflow/expansion tank. Coolant should be between MIN and MAX when cold. Top up with the specified coolant mixture (typically 50/50 ethylene glycol and distilled water) if low.
• Inspect for leaks: Look around radiator, hoses, hose clamps, water pump, and engine block for dried coolant residue or wet spots. Tighten loose clamps and replace cracked hoses.
• Check radiator cap: Inspect the radiator or reservoir cap seal for cracks or deformation. Replace if the spring is weak or seal is damaged.
• Coolant level sensor: Unplug the coolant level sensor on the expansion tank. Inspect connector pins for corrosion. Clean and reconnect. If the fault clears when the sensor is bypassed (for testing only), replace the sensor.
• Bleed air (if recently serviced): If the system was drained recently, follow the Kohler service manual bleeding procedure to remove trapped air (run with cap off until thermostat opens, topping up as needed, then reinstall cap).
• Reset and test: Reconnect battery, clear the fault on the controller, and run the unit while monitoring coolant level and temperature.

Persistent coolant loss or overheating indicates a deeper issue (e.g., head gasket, water pump) and should be inspected by a Kohler-certified technician.