Controller shows AL09 / Low Coolant Level and prevents automatic start.

Safety first: Allow the engine to cool completely before opening the cooling system. Set the controller to OFF and disconnect the battery negative terminal.

• Check coolant level: Remove the radiator cap or inspect the expansion tank on the Kohler-SDMO unit. Top up with the specified coolant mix to the correct mark.
• Inspect for leaks: Examine the radiator core, hoses, water pump weep hole, and engine block connections for dried coolant stains or wet spots. Tighten clamps and replace damaged hoses.
• Check coolant level sensor: Locate the level sensor on the radiator or header tank. Inspect the wiring and connector. Clean the sensor and reseat the connector. Replace the sensor if the alarm persists with the correct coolant level.
• Bleed air: If the system was very low, bleed air from bleed screws or high points as per the engine manual to prevent air locks.
• Reset alarm: Reconnect the battery, clear AL09, and run the generator while monitoring for leaks.

Repeated low coolant alarms indicate an unresolved leak or an overheating problem that should be investigated further.