Generator starts but immediately shuts down after a few seconds; no specific error code shown.

Safety first: Disable auto-start and keep the generator isolated from load while troubleshooting.

• Observe shutdown behavior: Watch the controller display during the brief run period for any transient warnings. Note whether shutdown occurs at the same time after start.
• Check fuel delivery: Monitor fuel pressure (if gauge is present) or listen for fuel pump operation. Replace clogged filters and verify that fuel solenoid remains energized after start.
• Inspect safety sensors: Temporarily monitor oil pressure and coolant temperature with mechanical gauges. If a sensor is falsely indicating a fault, replace the suspect sensor.
• Check run relay: Locate the run/hold relay that keeps the engine running after crank. Test its coil and contacts; replace if it drops out prematurely.
• Controller timing: Verify in the Siemens controller that warm-up and safety delay timers are set correctly. Incorrect settings can cause premature shutdown.