SHAFT AS 7W2081 - Caterpillar

Table 1
Diagnostic Trouble Codes for the NOx Sensors
J1939 Code CDL Code Code Description
(code descriptions may vary) Comments
3216-7 E1431 (2) Aftertreatment #1 Intake NOx : Not Responding Properly The engine out NOx level is not responding as expected.
The code is logged.
3226-7 E1432 (2) Aftertreatment #1 Outlet NOx : Not Responding Properly The tailpipe out NOx level is not responding as expected.
The code is logged.
Follow the troubleshooting procedure to identify the root cause of the problem.
Table 2
Required Tools
Tool Part Number Part Description Qty
A 441-0451 Tool Gp 1 During the following procedure, refer to the electrical schematic for the application.Complete the procedure in the order in which the steps are listed.
Table 3
Troubleshooting Test Steps Values Results
1. Check the Diesel Exhaust Fluid (DEF) Quality
A. Measure the DEF quality. Refer to Systems Operation, Testing and Adjusting, "Diesel Exhaust Fluid Quality - Test" for the correct procedure.
DEF Quality
Result: The DEF is not contaminated and the concentration is not within the acceptable range.
Repair: Drain the DEF from the tank. Refill the tank with DEF that meets ISO 22241 quality standards.
Proceed to Test Step 3.
Result: The DEF is not contaminated and the concentration is within the acceptable range.
Proceed to Test Step 2.
Result: The DEF is contaminated.
Repair: Contact the Dealer Solutions Network (DSN) for further information.
2. Perform a DEF Dosing System Accuracy Test
A. Perform a "DEF Dosing System Accuracy Test". Refer to Testing and Adjusting, "Aftertreatment SCR System Dosing - Test" for the correct procedure.
DEF Dosing System Accuracy Test
Result: The amount of DEF collected is within specification.
Repair: Install the DEF injector. Refer to Disassembly and Assembly, DEF Injector and Mounting - Remove and Install.
Proceed to Test Step 4.
Result: The amount of DEF collected is below specification.
Proceed to Test Step 3.
Result: The amount of DEF collected is above specification. A failed DEF injector has been detected.
Repair: Replace the DEF injector. Refer to Disassembly and Assembly, DEF Injector and Mounting - Remove and Install for the correct procedure.
Proceed to Test Step 4.
3. Check the DEF Pressure Line
A. Turn the keyswitch to the OFF position. Allow 2 minutes to elapse before proceeding.
B. Visually inspect the lines for leaks or damage.
C. Remove the DEF pressure line between the DEF pump and the DEF injector. Refer to the Disassembly and Assembly manual for the correct procedure.
D. Inspect the DEF pressure line for obstructions. Flush the line with water or low-pressure air, if necessary. Possible obstructions are ice, DEF deposits, or debris.
Restrictions, obstructions, or leaks
Result: There are restrictions or leaks in the lines.
Repair: Remove the restrictions or replace the pressure line.
Proceed to Test Step 4.
Result: There are no restrictions or leaks in the lines.
Repair: Proceed to Troubleshooting, "DEF Pressure is Low".
4. Perform an "Aftertreatment System Functional Test"
A. Connect the electronic service tool to the diagnostic connector.
B. Perform a "Aftertreatment System Functional Test".
Successful completion of test
Result: The test completed successfully.
Return the unit to service.
Result: The test did not complete successfully.
Proceed to Test Step 5.
5. Check for an Engine Misfire
A. Connect the electronic service tool to the diagnostic connector.
B. Use the electronic service