Engine speed fluctuates and unit shuts down, display shows E04 (over‑frequency / under‑frequency protection)

Safety first: Stop the generator, disconnect the spark plug cap, and allow hot components to cool before touching the engine.

• Inspect throttle and governor linkage: Locate the governor arm and linkage between the carburetor and engine. Move the linkage by hand; it should move smoothly without binding. Clean any dirt or rust and lightly lubricate pivot points with a dry lubricant (avoid excess oil near carburetor).
• Check governor spring: Ensure the governor spring is intact, not stretched, and correctly hooked into the specified holes on the governor arm and throttle lever as per the Einhell service diagram. Replace if deformed or broken.
• Clean carburetor main jet: Remove the carburetor bowl, unscrew the main jet, and clean it with carburetor cleaner and compressed air. Do not enlarge the jet orifices. Reassemble with a new bowl gasket if necessary.
• Verify no excessive load: Restart the generator with no load and observe frequency (if the Einhell display shows Hz). If frequency is stable at ~50 Hz (EU models) and E04 does not appear, gradually add load.
• Electronic governor (if fitted): If the unit uses an electronic governor module, inspect its wiring harness and connectors for damage. If frequency remains unstable with clean carburetion and free linkage, the governor module may require replacement.

Persistent E04 faults after these steps indicate the need for professional adjustment of the governor system by an Einhell service technician.