Controller shows AL05 / Low Fuel Level and prevents automatic start

Safety first: Disable automatic start and ensure no ignition sources are near the fuel system. Wear appropriate PPE.

• Verify actual fuel level: Open the access panel and visually inspect the base tank or external tank level gauge. If low, refill with clean diesel fuel to the recommended level.
• Inspect fuel level sensor: Locate the float-type or resistive fuel level sender on the tank top. Check the connector and wiring harness to the APM controller for corrosion, loose pins, or damage. Repair or replace as needed.
• Check sensor movement: Gently move the float arm (if accessible) to ensure it is not stuck. Clean any sludge or debris around the float mechanism.
• Controller calibration: In the APM controller configuration, verify that the fuel level sensor type and tank capacity are correctly set. Only adjust if you have the manufacturer's data.
• Reset alarm: After correcting fuel level or wiring, clear AL05 and test by cycling ignition and observing the fuel level indication on the display.

If the alarm persists with a full tank and good wiring, replace the fuel level sensor with a Kohler-SDMO compatible unit.