C175-16 Locomotive Engine Caterpillar

Use this procedure to troubleshoot a high Selective Catalyst Reduction (SCR) catalyst inlet pressure. Also, use this procedure if the following event code is active or logged.

Table 1

J1939 Code and Description	CDL Code and Description	Comments
6797-16 Aftertreatment #1 SCR Intake Absolute Pressure : High - moderate severity (2)	E1476 (2) High Aftertreatment #1 SCR Catalyst Intake Pressure	The SCR Catalyst Intake Pressure is above the normal operating range for aftertreatment bank #1.

Probable Causes

• Codes

• Exhaust system

• Deposits or buildup

Recommended Actions

Table 2

Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Apply electrical power to the engine. B. Connect Cat® Electronic Technician (ET) to the service tool connector. C. Look for active codes that are associated with the system for the event code.	Codes	Result: An associated code is active. Repair: Troubleshoot any associated codes before continuing with this test. Result: A code is active or logged. Proceed to Test Step 2.
2. Inspect the Exhaust System A. Remove electrical power from the engine. B. Visually inspect the exhaust system for damage between the Selective Catalyst Reduction (SCR) catalyst outlet and the tailpipe outlet.	Exhaust System	Result: The exhaust system is OK. Proceed to Test Step 3. Result: The exhaust system is NOT OK. Repair: Repair or replace damaged exhaust components. If the problem is not resolved, proceed to Test Step 3.
3. Inspect the SCR Catalyst A. Remove electrical power from the engine. B. Inspect the face of the SCR catalyst for the following: - Oil - Fuel - Urea deposits - Soot buildup	Deposits or Buildup	Result: The SCR catalyst face has oil, fuel, urea deposits, or soot buildup. Repair: Replace the damaged catalyst. For oil, refer to Troubleshooting, "Exhaust System Contains Oil" for additional information. For fuel, refer to Troubleshooting, "Exhaust System Contains Fuel" for additional information. For urea deposits, refer to Troubleshooting, "NOx Conversion is Low" "for additional information. For soot buildup, refer to Troubleshooting, "Exhaust Has Excessive Black Smoke" for additional information. Verify that the repair eliminated the problem.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).