Selective Catalytic Reduction Retrofit Aftertreatment Caterpillar

Use this procedure to troubleshoot a problem with high Diesel Exhaust Fluid (DEF) 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
6875-16 Aftertreatment #1 DEF Dosing Pressure : High - moderate severity (2)	E930 (2) High Aftertreatment #1 DEF Pressure	The Diesel Exhaust Fluid (DEF) pressure is above the threshold for proper system operation. DEF dosing is disabled.

Table 2

Associated Codes
J1939 Code	CDL Code	Troubleshooting Procedure
4335-15	E1969 (1)	Troubleshooting, "Air Assist Pressure Is High"
4335-17	E964 (1)	Troubleshooting, "Air Assist Pressure Is Low"
4335-18	E964 (2)	Troubleshooting, "Air Assist Pressure Is Low"
4335-3	3092-3	Troubleshooting, "Sensor Signal (Analog, Active) - Test"
4335-4	3094-4	Troubleshooting, "Sensor Signal (Analog, Active) - Test"
4376-5	3862-5	Troubleshooting, "Solenoid Valve - Test"
4376-6	3862-6	Troubleshooting, "Solenoid Valve - Test"
6875-3	3090-3	Troubleshooting, "Sensor Signal (Analog, Active) - Test"
6875-4	3090-4	Troubleshooting, "Sensor Signal (Analog, Active) - Test"
7107-5	N/A	Troubleshooting, "DEF Pump Motor - Test"
7107-6	N/A	Troubleshooting, "DEF Pump Motor - Test"
7107-11	N/A	Troubleshooting, "DEF Pump Motor - Test"
7416-5	N/A	Troubleshooting, "Solenoid Valve - Test - Aftertreatment"
7416-6	N/A	Troubleshooting, "Solenoid Valve - Test - Aftertreatment"
7417-2	N/A	Troubleshooting, "DEF Pump Power Supply - Test"
7417-5	N/A	Troubleshooting, "Circuit Breaker - Test"
7417-6	N/A	Troubleshooting, "Circuit Breaker - Test"

Illustration 1	g03746847
Diesel Exhaust Fluid (DEF) dosing control cabinet components Valves are shown in a static state (1) DEF line to injector at CEM (2) Air line to injector at CEM (3) Compressed air source (customer supplied) (4) DEF source (customer supplied) (5) DEF pressure sensor (6) Air assist pressure sensor (7) Air pressure regulator (8) Air assist valve (9) DEF buffer tank return valve (10) DEF buffer tank fill valve (11) DEF pump (12) DEF level sensor (13) DEF buffer tank

Illustration 2	g03747254
Enhanced Troubleshooting Information (ETI) code

Probable Causes

• Codes

• Sensor

• DEF line

• DEF injector

• DEF pump

Recommended Actions

Table 3

Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Turn the DC breaker to the ON position. 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. Record the Enhanced Troubleshooting Information (ETI) code with the event. Refer to Illustration 2 for the ETI code location. Proceed to Test Step 2.
2. Monitor the Catalyst Intake Gas Temperature A. Turn the DC breaker to the ON position. B. Connect Cat ET. C. Use Cat ET to monitor the following temperature: - "Aftertreatment #1 SCR Catalyst Intake Gas Temperature"	Temperature	Result: The "Aftertreatment #1 SCR Catalyst Intake Gas Temperature" is less than 180° C (356° F) Proceed to Test Step 3. Result: The "Aftertreatment #1 SCR Catalyst Intake Gas Temperature" is 180° C (356° F) or higher. Repair: Use Cat ET to perform the following override: - Set the "Aftertreatment #1 SCR Dosing Air Assist Valve Command Override" to the OFF position. Proceed to Test Step 3.
3. Check the DEF Pressure Sensor A. Turn the DC breaker to the ON position. B. Connect Cat ET. C. Use Cat ET to monitor the following pressure: - "Aftertreatment #1 DEF Dosing Pressure"	Sensor	Result: The DEF pressure sensor reads 0 ± 20 kPa (0 ± 3 psi). Proceed to Test Step 4. Result: The DEF pressure sensor does not read 0 ± 20 kPa (0 ± 3 psi). Repair: Replace the DEF pressure sensor. Proceed to Test Step 8.
4. Determine the ETI Code A. Use the ETI code recorded in Step 1 to determine the troubleshooting.	Code	Result: An ETI code of 4 is present. Proceed to Test Step 5. Result: An ETI code of 1 is present. Repair: A failed DEF injector has been detected. Replace the DEF injector. Proceed to Test Step 8. Result: An ETI code of 2 is present. Repair: A failed DEF return valve has been detected. Replace the DEF return valve. Proceed to Test Step 8. Result: An ETI code of 3 is present. Repair: A failed DEF pump has been detected. Replace the DEF pump. Proceed to Test Step 8.
5. Inspect the DEF Pressure Line A. Turn the DC breaker to the OFF position. B. Disconnect the DEF pressure line from the dosing cabinet. C. Disconnect the DEF pressure line from the DEF injector. D. Pour warm water through the DEF pressure line and verify that the line is not blocked.	DEF Line	Result: The DEF pressure line is not blocked. Proceed to Test Step 6. Result: The DEF pressure line is blocked. Repair: Replace the DEF pressure line. Proceed to Test Step 8.
6. Inspect the DEF Injector for Plugging A. Turn the DC breaker to the OFF position. B. Disconnect the DEF supply line at the DEF injector. C. Remove the DEF injector from the exhaust. D. Inspect the DEF injector for signs of plugging.	DEF Injector	Result: The DEF injector is not plugged. Proceed to Test Step 7. Result: The DEF injector is plugged. Repair: Replace the DEF injector. Proceed to Test Step 8.
7. Replace the DEF Pump A. Turn the AC and DC breakers to the OFF position. B. Replace the DEF pump	DEF Pump	Result: The DEF pump was replaced. Proceed to Test Step 8.
8. Perform a "DEF Dosing System Verification Test" A. Turn the AC and DC breakers to the ON position. B. Connect Cat ET. C. Use Cat ET to perform the following diagnostic test: - "DEF Dosing System Verification Test"	Test	Result: The test was successful and the 6875-16 code cleared. Return to service.

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).