Controller shows F28 Crank Disconnect Fault; starter remains engaged too long or disengages too early.

Safety first: A starter that remains engaged with a running engine can cause severe damage. Do not repeatedly attempt to start until the issue is resolved.

• Observe start sequence: During a start attempt, listen for the starter disengaging as the engine fires. If it grinds or stays engaged, stop the attempt immediately.
• Check speed sensor: If the controller does not detect that the engine has started, it may keep cranking. Inspect and test the engine speed sensor and its wiring.
• Inspect starter solenoid: A sticking solenoid can keep the starter engaged. Replace the starter or solenoid if mechanical sticking is suspected.
• Verify crank settings: In the controller configuration, confirm that crank time and rest time parameters are set according to Siemens specifications.
• Controller output test: If the starter output remains energized after the engine is running, the controller relay or transistor may be faulty and require controller replacement.