HEAD 4220208 - Caterpillar

Table 1
J1939 Code and Description CDL Code and Description Comments
6797-15
Aftertreatment #1 SCR Intake Absolute Pressure : High - moderate severity (2) E1476 (1)
High Aftertreatment #1 SCR Catalyst Intake Pressure The Selective Catalyst Reduction (SCR) Catalyst Intake Pressure is above the normal operating range for aftertreatment bank #1.
6798-15
Aftertreatment #2 SCR Intake Absolute Pressure : High - moderate severity (2) E1477 (1)
High Aftertreatment #2 SCR Catalyst Intake Pressure The SCR Catalyst Intake Pressure is above the normal operating range for aftertreatment bank #2. Probable Causes
Codes
Exhaust system
Deposits or buildupRecommended Actions
Illustration 1 g06302052
Clean Emissions Module (CEM)
(1) Catalyst
(2) Mixer
(3) Diffuser plate
Illustration 2 g06302055
CEM
(1) Catalyst
(2) Mixer
Table 2
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Turn the keyswitch to ON.
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. Turn the keyswitch to OFF.
B. Visually inspect the affected bank of 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 Mixer and Catalyst
A. Turn the keyswitch to OFF.
B. Inspect the faces of the SCR catalysts and mixers on the affected exhaust bank for the following:
- Oil
- Fuel
- Urea deposits
- Soot buildup
Deposits or Buildup
Result: There is oil, fuel, urea deposits, or soot buildup.
Repair: Replace the damaged components.
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 build up, 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).