Controller displays E04 / OVERSPEED and the generator shuts down abruptly during or shortly after start.

Safety first: Disable AUTO mode and isolate generator output by opening the generator breaker. Overspeed can cause severe damage; do not repeatedly restart until the cause is identified.

• Inspect throttle and governor: With engine off, move the throttle lever and governor linkage by hand. They should move smoothly and return by spring tension. Lubricate lightly if sticking; remove any debris or corrosion.
• Check speed sensor: Locate the magnetic pickup / engine speed sensor near the flywheel or ring gear. Inspect the connector and wiring harness for damage. Ensure the sensor is mounted at the correct gap specified by Winco (often 0.020–0.040 in).
• Controller settings: Verify that no unauthorized changes were made to rated frequency or speed parameters in the Winco controller. Compare to the factory settings in the service manual.
• Test no-load run: Start the generator in MANUAL with no load and listen for abnormal racing. If the engine immediately revs excessively, shut it down and do not continue. The electronic governor module or mechanical governor may be faulty.

Because overspeed can cause catastrophic failure, if E04 repeats after basic checks, have a qualified generator technician test the governor system and controller.