C175-16 Locomotive Engine Caterpillar

Use this procedure to troubleshoot a problem with the NOx level being monitored. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.

The Electronic Control Module (ECM) is monitoring the NOx level being reported by the sensor. If the NOx value is not steady when the engine speed/fueling is steady, the codes listed below will log. If the NOx value is steady when the engine speed/load is changing, the codes listed below will log.

Table 1

J1939 Code and Description	CDL Code and Description	Comments
3216-7 Aftertreatment #1 Intake NOx : Not Responding Properly	E1431 (2) Invalid Aftertreatment #1 Intake NOx Level	The aftertreatment intake NOx level is not responding as expected. The code is logged.
3226-7 Aftertreatment #1 Outlet NOx : Not Responding Properly	E1432 (2) Invalid Aftertreatment #1 Outlet #1 NOx Level	The aftertreatment outlet NOx level is not responding as expected. The code is logged.

Table 2

Required Tools
Qty	Part Number	Part Description
1	431-7087	Tool Gp
1	441-0451	Tool Gp

Table 3

Troubleshooting Test Steps	Values	Results
1. Check the Diesel Exhaust Fluid (DEF) quality. A. Measure the DEF quality. Refer to Testing and Adjusting, "Diesel Exhaust Fluid Quality - Test" for additional information.	DEF Quality	Result: The DEF is not contaminated and the concentration is within the acceptable range. Proceed to Test Step 2. 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 contaminated. Repair: Contact the Dealer Solution Network (DSN) for further information.
2. Perform a DEF Dosing System Accuracy Test Note: Shore power must be present while performing this step in order for the DEF pump to have power. A. Connect Cat® Electronic Technician (ET) to the service tool connector. B. Use Cat ET to perform the following dosing test: - "DEF Dosing System Accuracy Test" Refer to Testing and Adjusting, "DEF Dosing System Accuracy Test" for additional information. Note: While performing this test, the test hose can contain up to an extra 140 mL (4.76 oz) of fluid. If this fluid drains into the test container, the total volume of DEF will be 2145 ± 200 mL.	2 L ± 200 mL	Result: The amount of DEF collected was below 2 L ± 200 mL. Repair: Replace the failed DEF pump. Refer to Disassembly and Assembly for additional information. Proceed to Test Step 3. Result: The amount of DEF collected was 2 L ± 200 mL of DEF. Proceed to Test Step 3. Result: The amount of DEF collected was above 2 L ± 200 mL. A failed DEF pump has been detected. Repair: Replace the failed DEF pump. Refer to the Disassembly and Assembly manual for additional information. Proceed to Test Step 3.
3. Perform an "Aftertreatment System Functional Test" A. Connect Cat ET. B. Use Cat ET to perform the following dosing test: - "Aftertreatment System Functional Test"	Dosing Test	Result: The test completed successfully. 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).