Kohler Locked Rotor Alarm
Locked Rotor — Shutdown Alarm The Locked Rotor alarm means the controller sent a start command but detected no engine rotation within the preset time window (typically 2–3 seconds). To protect the starter motor from damage, the controller halts all crank attempts and locks out the unit until the fault is cleared. Despite the alarming name, the engine itself is often not physically seized — the most common cause is a weak or dead battery or a failed speed sensor. Dead or weak 12V battery (most common — 90% of cases) Failed magnetic pickup / speed sensor (no rotation signal) Faulty or stuck starter motor or solenoid Loose, corroded, or unseated wiring harness connectors Physically seized engine (debris, corrosion, extended storage) Worn or misaligned brushes / slip rings (generator end) Faulty controller / outdated controller firmware Faulty battery charger — not maintaining battery charge
