Controller displays F20 – Stop failure, engine continues running after stop command

Safety first: Be prepared to use an emergency stop if the engine does not respond to normal stop commands.

• Test stop command: Issue a stop from the controller and observe whether the fuel shutoff solenoid or actuator moves to the stop position.
• Inspect fuel shutoff device: Locate the fuel shutoff solenoid on the MTU engine. Check for mechanical binding, contamination, or weak return spring.
• Check stop relay and wiring: Verify that the stop relay energizes/de-energizes correctly and that wiring from the controller to the solenoid is intact.
• Manual stop test: If safe and per MTU procedures, manually move the fuel rack or shutoff lever to confirm the engine stops. If it does, the problem is likely electrical.
• Replace faulty components: Replace a defective fuel shutoff solenoid or stop relay with MTU-approved parts.
• Re-test: Clear the F20 alarm and verify proper stop operation from the controller.