Generator starts but stops within a few seconds and the display shows E08.

Safety first: Turn OFF the generator and disconnect the battery negative cable.

• Locate the RPM sensor: On Firman standby generators, the RPM or tach sensor is typically mounted near the flywheel housing. Refer to your model's service diagram.
• Inspect sensor and wiring: Check that the sensor is firmly mounted and not contacting the flywheel. Inspect the harness for cuts, abrasions, or oil contamination. Clean the connector and reseat it.
• Check sensor gap: Use a feeler gauge to verify the air gap between the sensor tip and the flywheel teeth/reluctor ring is within the specification (often around 0.5–1.0 mm). Adjust if necessary.
• Test sensor resistance: With the sensor unplugged, measure resistance across its terminals. Compare to Firman specifications. Replace the sensor if open, shorted, or out of range.

Reconnect the battery, clear E08, and test. If the fault remains with a new sensor and good wiring, the controller's RPM input circuit may be defective and require replacement.