RPM Sense Loss
Generac
Loss of engine speed signal to controller
Generator cranks and may briefly fire, then shuts down with 'RPM Sense Loss' alarm.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Defective RPM sensor, Loose or damaged RPM sensor wiring, Faulty controller input circuit, Excessive air gap between sensor and flywheel
How to Fix / Troubleshooting
Safety: Turn the generator OFF and disconnect the battery negative cable before working near the flywheel or rotating parts.
- Locate RPM sensor: Find the magnetic pickup or Hall-effect sensor mounted near the flywheel ring gear. Inspect for physical damage or metal shavings on the tip.
- Clean and adjust: Clean the sensor tip and verify the air gap to the flywheel teeth is within Generac specifications (often around 0.020–0.040 in, but confirm in manual). Adjust mounting if necessary.
- Check wiring: Trace the sensor harness back to the controller. Look for chafed insulation, loose connectors, or corrosion. Repair or replace damaged wiring.
- Replace sensor: If the sensor tests open or shorted with an ohmmeter, or if the alarm persists after cleaning and adjustment, replace the RPM sensor with the correct Generac part.
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Repair Difficulty
Medium
3/5
Required Part
Engine Speed Sensor
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