C3.4B Engines Caterpillar

Desulfation Is Frequent

Usage:

CCS7 4B2

This procedure covers the following diagnostic code:

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Table 1
Diagnostic Trouble Codes for Desulfation Is Frequent
J1939 Code	Description	Notes
6322-31	Aftertreatment #1 SCR Desulfation too Frequent	The engine has attempted to burn off sulphur deposits in the aftertreatment system three times without success.
6935-15	Aftertreatment #1 SCR System Total Cleaning Time : High Least Severe (1)	The engine has attempted to burn off sulphur deposits in the aftertreatment system three times without success. The warning lamp will come on.
Follow the troubleshooting procedure to identify the root cause of the problem.

Complete the procedure in the order in which the steps are listed.

Aftertreatment Sulfation Recovery Procedure

Note: Electronic service tool version 2017B or later is required to perform this procedure.

Note: Use the electronic service tool to disable "Engine Idle Shutdown" and/or "User Defined Shutdown", if enabled, before performing this procedure. This action prevents the engine from shutting down immediately after the procedure has completed and allows a sufficient cool-down period.

The "Aftertreatment Sulfation Recovery Procedure" is designed to clear sulfate deposits that have built up in the Selective Catalytic Reduction (SCR) aftertreatment. Part 2 of the procedure is used to clear the diagnostic code and remove the warning lamp. Part 1 of the procedure must be performed before part 2.

When safety interlocks are in place, the procedure works by taking control of the engine. A sequence of tests is performed to elevate exhaust temperatures and ensure that optimal conditions are met to reduce sulfate levels. Once sulfate levels are reduced to the required level, the procedure will complete.

Note: After the procedure has completed, allow a sufficient cool-down period at low idle before stopping the engine. Refer to Operation and Maintenance Manual, Stopping the Engine for more information.

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Table 2
Possible Error Messages Generated During the Aftertreatment Sulfation Recovery Procedure
Description	Notes	Temperature Related
Coolant Temperature must be between 75° C (167° F) and 100° C (212° F)	The service procedure has been run, but has not been able to complete due to coolant temperature outside of parameters.	Yes (Refer to Troubleshooting, Coolant Temperature Is Low or Troubleshooting, Coolant Temperature Is High).
Barometric Pressure must be greater than 80 kPa (11.6 psi)	The service procedure has been run, but has not been able to complete due to barometric pressure outside of parameters.	No
Aftertreatment #1 Diesel Oxidation Catalyst Intake Temperature must be between 180° C (356° F) and 550° C (102° F).	The service procedure has run, but has not been able to complete due to Diesel Oxidation Catalyst (DOC) intake temperature outside of parameters.	Yes (Refer to Troubleshooting, Exhaust System Contains DEF Deposits).
Aftertreatment #1 SCR Catalyst Intake Gas Temperature must be between 180° C (356° F) and 550° C (102° F)	The service procedure has been run, but as not been able complete due to SCR intake gas temperature outside of parameters.	Yes (Refer to Troubleshooting, Exhaust System Contains DEF Deposits).
"Machine Idle Status must be in the Idle state"	The service procedure has been run, but has not been able to complete due to machine idle state not being set.	No
"Machine must be parked and the parking brake must be set"	The service procedure has been run, but has not been able to complete due to the machine not being parked and the parking brake not set.	No
"The clutch pedal must NOT be pressed"	The service procedure has been run, but has not been able to complete due to the clutch pedal being pressed.	No
"Transmission Gear must be in Neutral"	The service procedure has been run, but has not been able to complete due to the transmission gear not being in neutral.	No

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Table 3
Troubleshooting Test Steps	Values	Results
1. Check for Diagnostic Codes Note: Ensure that electronic service tool version 2017B or later is being used. A. Connect to the electronic service tool. B. Check for active or recently logged diagnostic codes.	Diagnostic Codes	Result: A diagnostic code other than those codes listed in Table 1 is active or recently logged. Troubleshoot the additional diagnostic codes. Refer to Troubleshooting, "Diagnostic Trouble Codes". Result: One of the diagnostic codes listed in Table 1 is active. Repair: Proceed to Test Step 2.
2. Perform the "Aftertreatment Sulfation Recovery Procedure - Part 1" A. Use the electronic service tool to disable "Engine Idle Shutdown" and/or "User Defined Shutdown", if enabled, before performing this procedure. This action prevents the engine from shutting down immediately after the procedure has completed and allows a sufficient cool-down period. B. Use the electronic service tool to perform the "Aftertreatment Sulfation Recovery Procedure - Part 1". Note: After the procedure has completed, allow a sufficient cool-down period at low idle before stopping the engine. Refer to Operation and Maintenance Manual, Stopping the Engine for more information.	"Aftertreatment Sulfation Recovery Procedure - Part 1"	Result: The "Aftertreatment Sulfation Recovery Procedure - Part 1" did not complete successfully. Proceed to Test Step 3. Result: The "Aftertreatment Sulfation Recovery Procedure - Part 1" completed successfully. Proceed to Test Step 4.
3. Confirm the "Aftertreatment Sulfation Recovery Procedure - Part 1" Error Messages A. Determine whether error messages that were displayed during "Aftertreatment Sulfation Recovery Procedure - Part 1" are temperature-related. Refer to Table 2.	Parameters not met	Result: The error message is not temperature-related. After up to 3 hours, the "Aftertreatment Sulfation Recovery Procedure - Part 1" is unable to complete successfully. Repair: Ensure that the parameters for the test are met. Refer to Table 2 for more information. Repeat this procedure from Test Step 1. Result: The error message is temperature-related. Repair: Perform the appropriate troubleshooting procedure. Refer to Table 2 for more information. Repeat this procedure from Test Step 1.
4. Perform the "Aftertreatment Sulfation Recovery Procedure - Part 2" Note: "Aftertreatment Sulfation Recovery Procedure - Part 1" must be completed before attempting this step. A. Use the electronic service tool to perform the "Aftertreatment Sulfation Recovery Procedure - Part 2". If the "Aftertreatment Sulfation Recovery Procedure - Part 1" did not complete successfully or the "SCR Sulfur Percentage" is greater than 15%, the following message will be displayed and the test will not complete: "SCR Sulfur Percentage Too High"	Test successful	Result: The test has completed successfully. Sulfur deposits in the SCR system have been cleared successfully. The diagnostic code and warning lamp related to SCR desulfation issues have been cleared. Note: This procedure will not clear other diagnostic codes such as operator inducement codes. Return the engine to service. Repair: The test did not complete successfully. Contact the Dealer Solutions Network (DSN).