Generator will not start and the controller displays E01 immediately after a start attempt.

Safety first: Turn the generator OFF, set the AUTO/OFF/MANUAL switch to OFF, disconnect the negative battery cable, and allow the engine to cool completely before working on it.

• Check oil level: Remove the dipstick and verify that the oil level is between the LOW and FULL marks. Top up with the manufacturer‑specified oil (typically SAE 10W‑30 or as listed in your DuroStar manual). Do not overfill.
• Inspect for leaks: Look around the oil filter, drain plug, crankcase gasket, and oil cooler (if equipped) for wet oil spots. Tighten the drain plug and oil filter by hand plus 3/4 turn if loose. Repair obvious leaks before restarting.
• Reset and test: Reconnect the battery, clear the code if your controller has a reset function, then attempt a manual start. If the unit starts and runs normally, monitor for further leaks.
• Check low oil pressure switch: Locate the low oil pressure switch on the engine block (usually near the oil filter). Disconnect the wire and check continuity to ground with a multimeter. With the engine OFF, the switch is usually closed to ground; if it reads open or shorted at all times, replace the switch.
• Inspect wiring: Trace the harness from the low oil switch to the control board for pinched, cut, or corroded wires. Repair or replace damaged sections and ensure connectors are fully seated.
• If oil level and switch are OK: Do not continue to crank the engine; internal lubrication problems may exist. Contact a qualified generator technician to test oil pressure with a mechanical gauge.