Perkins generator controller displays E009 and indicates low coolant level

Safety: Allow the engine to cool fully before opening the cooling system. Pressurized hot coolant is dangerous.

• Verify coolant level: Check the sight glass or expansion tank level. If low, top up with the correct coolant mix and then look for the cause of loss.
• Inspect for external leaks: Examine all hoses, clamps, radiator core, water pump weep hole, and heater lines for signs of dried coolant or wetness. Tighten or replace components as needed.
• Check coolant level sensor: Locate the level probe or float switch in the header/expansion tank. Disconnect the plug and bridge the harness terminals to simulate a full condition (if safe and per manual). If the alarm clears, the sensor is likely faulty.
• Test radiator cap: Inspect the cap seal and spring. A failed cap can allow boiling and loss of coolant. Replace with the correct pressure‑rated cap.
• Reset alarm: After topping up and fixing leaks, clear E009 on the controller and run the engine while monitoring for further level drop.