E06
Firman Over-Speed / Under-Speed Protection

Generator shuts down and displays E06; engine speed appears too high or too low before shutdown.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Faulty engine speed sensor (magnetic pickup), Sticking or misadjusted governor linkage, Defective electronic governor module, Loose throttle linkage at carburetor or injection pump

How to Fix / Troubleshooting

Safety first: Turn OFF the generator, disconnect battery negative, and ensure the unit cannot auto-start.

  • Inspect governor linkage: Locate the mechanical governor arm and linkage between the engine and carburetor or injection pump. Check for binding, rust, or debris. Lubricate pivot points lightly and ensure the return springs are intact.
  • Check throttle plate movement: Manually move the throttle lever at the carburetor/injection pump to confirm smooth travel from idle to full. Correct any obstructions or bent linkage.
  • Inspect speed sensor: On many Firman standby units, a magnetic pickup sensor is mounted near the flywheel or ring gear. Check the sensor tip gap (usually 0.5–1.0 mm) and clean off metal shavings. Ensure the connector is tight and wiring is not damaged.
  • Reset controller: After mechanical checks, reconnect the battery, clear the E06 code, and start the generator while monitoring RPM or frequency (should be ~60 Hz). If speed still hunts or trips, the electronic governor module may be faulty.

Governor calibration and module replacement are best done by a qualified technician with access to Firman service procedures.

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Repair Difficulty

Hard 4/5

Required Part

Engine Speed Sensor (Magnetic Pickup)
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