Generator stops and displays E07; AC output voltage is abnormally high or low before shutdown.

Safety first: Turn OFF the generator, disconnect battery, and lock out the transfer switch to prevent backfeed. Use insulated tools when working near AC terminals.

• Measure output voltage: With a multimeter rated for the generator's voltage, verify line‑to‑line and line‑to‑neutral voltages when the unit is running with no load. Compare to the nameplate rating.
• Inspect AVR connections: Locate the automatic voltage regulator inside the alternator housing or control compartment. Check all plug‑in connectors for tightness and corrosion. Reseat connectors firmly.
• Check stator and rotor leads: Inspect the wiring from the stator windings and rotor brushes (if equipped) to the AVR and terminal block. Tighten any loose terminals and repair damaged insulation.
• Test/replace AVR: If voltage is unstable or out of range with correct engine speed, the AVR is a common failure point. Replace it with a DuroStar‑specified AVR module and retest.
• Verify engine speed: Use a frequency meter to ensure the engine is running at the correct RPM (typically 60 Hz output). Adjust the governor if necessary per the service manual.
• If problem persists: The alternator windings or control board voltage sensing circuit may be faulty. Further testing with insulation resistance and winding resistance measurements by a technician is recommended.