C175 Petroleum Engine Caterpillar

Note: Refer to the appropriate troubleshooting procedure in the troubleshooting guide for additional information.

When operating the engine outside of the regulatory areas of the EPA/IMO for an extended period of time, this procedure must be performed to prevent damage to the Selective Catalytic Reduction (SCR) system.

Follow the steps in the order below to ensure that SCR system is purged of all Diesel Exhaust Fluid (DEF). DEF will crystallize and potentially damage the components in the SCR system, if the DEF is left in the system for an extended period of time.

1. Make sure that the engine is turned OFF and not running.

2. Turn the DC breaker to the ON position.

3. Connect Cat^® Electronic Technician (ET) to the service tool connector.

4. Use the "Aftertreatment System Enable Status" feature in Cat ET to turn the aftertreatment system to the "Disabled" state. Factory passwords are required.

5. Turn the DC breaker to the OFF position.

6. Turn the shutoff valve for the customer DEF supply to the dosing cabinet to the OFF position.

7. Disconnect the DEF supply line from the customer tank at the dosing cabinet.

8. Turn the DEF transfer pump OFF (if equipped).

9. Turn the AC and DC breaker to the ON position.

10. Use Cat ET to perform the following procedure:

    A. With the air supply to the dosing cabinet ON, use Cat ET to perform the "Aftertreatment #1 Dosing Air Assist Valve Command Override".

    Perform this override for 30 seconds. This override will clear the DEF from the DEF lines and to push the DEF back into the dosing cabinet DEF tank.

    B. Leave the "Aftertreatment #1 Dosing Air Assist Valve Command Override" ON. Then, perform the "Aftertreatment #1 DEF Tank Refill Solenoid Override" for 30 seconds to clear the DEF manifold and the DEF supply line of any remaining DEF.

11. Turn the AC and DC breaker to the OFF position.

12. Disconnect the NOx sensors from the wiring harness and remove the NOx sensors from the exhaust piping. Plug the NOx sensor ports with an appropriate plug. Refer to REHS8151 for proper NOx sensor handling procedures.

13. Disconnect the DEF line and the air supply line at the DEF injector. The air supply line at the DEF injector must be capped.

14. Remove the DEF injector from the exhaust stream and cover the DEF injector mounting port.

15. Disconnect the remaining DEF supply lines at the DEF dosing cabinet. The air supply line to the dosing cabinet and the air supply line to the DEF injector must remain installed.

16. Use the DEF line from the 464-1955 Tool Case As. Connect the DEF line to the DEF dosing cabinet and route the DEF line into a suitable container.

17. Turn the AC and DC breaker to the ON position.

18. Perform the "Aftertreatment Decommissioning Service Test" and follow the instructions within the service test. Allow the DEF and water to drain into a suitable container.

19. The AC and DC power must remain ON during engine operation even though the aftertreatment system is not functioning. This allows the ECM to track how long the SCR catalysts have been aged.

    The engine is now prepared to run for extended periods of time without damage outside of the EPA/IMO regulatory areas.

    Note: The SCR catalysts will continue to age when left in the exhaust system. The SCR catalysts may be removed from the exhaust system to preserve the SCR catalysts for a longer period of time. Refer to Disassembly and Assembly, "SCR Catalyst Removal" for additional information.

    Note: The pressure and temperature sensors in the SCR system must not be removed. The pressure and temperature sensors will still function and provide warning if damage could occur to the SCR catalyst.