Generator shuts down during operation and displays E4 on the controller

Safety first: Overspeed conditions are dangerous. Turn the controller to OFF, open the main AC breaker, and disconnect the negative battery cable. Do not attempt to run the generator until the cause is identified.

• Inspect throttle linkage: Remove the side panel and visually inspect the throttle plate, governor arm, and linkage rods. Ensure they move freely and are not binding due to rust, dirt, or misrouting. Lubricate pivot points lightly with a non-gumming lubricant.
• Check governor spring: Verify the governor spring is intact, properly hooked, and not stretched or missing. Replace if deformed or broken.
• Look for aftermarket modifications: Confirm no one has altered the governor setting or installed non-OEM springs. Restore to factory configuration using the Westinghouse service manual specifications.
• Inspect engine speed sensor: Locate the magnetic pickup or Hall-effect speed sensor near the flywheel or ring gear. Check for loose mounting, damaged wiring, or metal debris on the sensor tip. Clean and reseat as needed.
• Controller calibration: Some controllers allow RPM calibration. If recently serviced, verify that the correct frequency (50/60 Hz) and speed parameters are set. Incorrect settings can falsely trigger overspeed.

If E4 persists after mechanical checks, do not continue to run the unit. Have a technician verify actual engine RPM with a tachometer and adjust or replace the governor or control board as required.