C175 Tier 4 Final Engines for Off-Highway Trucks Caterpillar

DEF Temperature Is Low

Usage:

793F D3T

Use this procedure to troubleshoot a low Diesel Exhaust Fluid (DEF) temperature. Also, use this procedure if one of the following event codes is active or logged.

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Table 1
J1939 Code and Description	CDL Code and Description	Comments
3031-7 Aftertreatment #1 DEF Tank Temperature : Not Responding Properly	E1441 (1) Aftertreatment #1 DEF Tank Temperature #1 Not Responding	The Aftertreatment #1 Diesel Exhaust Fluid Control Unit (DCU) detects that the #1 Diesel Exhaust Fluid (DEF) tank temperature is not responding properly. The code is logged.
3031-17 Aftertreatment #1 DEF Tank Temperature : Low - moderate severity (2)	E1398 (1) Low Aftertreatment #1 DEF Tank Temperature #1	The Aftertreatment #1 DCU #1 detects that the DEF tank temperature is lower than expected. The code is logged.
4427-7 Aftertreatment #2 DEF Tank Temperature : Not Responding Properly	E1742 (1) Aftertreatment #2 DEF Tank Temperature #1 Not Responding	The Aftertreatment #2 DCU #1 detects that the DEF tank temperature is not responding properly. The code is logged.
4427-17 Aftertreatment #2 DEF Tank Temperature : Low - moderate severity (2)	E1400 (1) Low Aftertreatment #2 DEF Tank Temperature #1	The Aftertreatment #2 DCU #1 detects that the DEF tank temperature is lower than expected. The code is logged.
5798-7 Aftertreatment #1 DEF Dosing Unit Heater Temperature : Not Responding Properly	E1427 (1) Aftertreatment #1 DEF Dosing Unit #1 Temperature Not Responding	The Aftertreatment #1 DCU #1 detects that the DEF pump temperature sensor is not responding properly. The code is logged.
7543-7 Aftertreatment #1 DEF Dosing Unit #2 Heater Temperature : Not Responding Properly	E1700 (1) Aftertreatment #1 DEF Dosing Unit #2 Temperature Not Responding	The Aftertreatment #1 DCU #2 detects that the DEF pump temperature sensor is not responding properly. The code is logged.
7544-7 Aftertreatment 2 Diesel Exhaust Fluid Dosing Unit 1 Heater Temperature : Not Responding Properly	E1701 (1) Aftertreatment #2 DEF Dosing Unit #1 Temperature Not Responding	The Aftertreatment #2 DCU #1 detects that the DEF pump temperature sensor is not responding properly. The code is logged.
7545–7 Aftertreatment 2 Diesel Exhaust Fluid Dosing Unit 2 Heater Temperature : Not Responding Properly	E1702 (1) Aftertreatment #2 DEF Dosing Unit #2 Temperature Not Responding	The Aftertreatment #2 DCU #2 detects that the DEF pump temperature sensor is not responding properly. The code is logged.
7572-7 Aftertreatment #1 DEF Tank Temperature #2 : Not Responding Properly	E1741 (1) Aftertreatment #2 DEF Dosing Unit #1 Temperature Not Responding	The Aftertreatment #1 DEF tank Temperature #2 is not responding properly. The code is logged.
7572-17 Aftertreatment #1 DEF Tank Temperature #2 : Low - moderate severity (2)	E1697 (1) Low Aftertreatment #1 DEF Tank Temperature #2	The Aftertreatment #1 DCU #2 detects that the DEF tank temperature is lower than expected. The code is logged.
7574–7 Aftertreatment #2 DEF Tank Temperature #2 : Not Responding Properly	E1743 (1) Aftertreatment #2 DEF Dosing Unit #2 Temperature Not Responding	The Aftertreatment #2 DEF tank Temperature #2 is not responding properly. The code is logged.
7574–17 Aftertreatment #2 DEF Tank Temperature #2 : Low - moderate severity (2)	E1699 (1) Low Aftertreatment #2 DEF Tank Temperature #2	The Aftertreatment #2 DCU #2 detects that the DEF tank temperature is lower than expected. The code is logged.

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Table 2
Associated Codes
J1939 Code	CDL Code	Troubleshooting Procedure
3363-5	3126-5	Troubleshooting, "Solenoid Valve - Test (Aftertreatment)"
3363-6	3126-6	Troubleshooting, "Solenoid Valve - Test (Aftertreatment)"
4354-5	3110-5	Troubleshooting, "DEF Line Heater - Test"
4354-6	3110-6	Troubleshooting, "DEF Line Heater - Test"
4355-5	3111-5	Troubleshooting, "DEF Line Heater - Test"
4355-6	3111-6	Troubleshooting, "DEF Line Heater - Test"
4356-5	3112-5	Troubleshooting, "DEF Line Heater - Test"
4356-6	3112-6	Troubleshooting, "DEF Line Heater - Test"
4357-5	3113-5	Troubleshooting, "DEF Line Heater - Test"
4357-6	3113-6	Troubleshooting, "DEF Line Heater - Test"
5491-5	3822-5	Troubleshooting, "DEF Line Heater - Test"
5491-6	3822-6	Troubleshooting, "DEF Line Heater - Test"
7069-5	4835-5	Troubleshooting, "DEF Line Heater - Test"
7069-6	4835-6	Troubleshooting, "DEF Line Heater - Test"
7562-5	4841-5	Troubleshooting, "DEF Line Heater - Test"
7562-6	4841-6	Troubleshooting, "DEF Line Heater - Test"
7563-5	4843-5	Troubleshooting, "DEF Line Heater - Test"
7563-6	4843-6	Troubleshooting, "DEF Line Heater - Test"
7565-5	4844-5	Troubleshooting, "DEF Line Heater - Test"
7565-6	4844-6	Troubleshooting, "DEF Line Heater - Test"
7573-5	5011-5	Troubleshooting, "Solenoid Valve - Test (Aftertreatment)"
7573-6	5011-6	Troubleshooting, "Solenoid Valve - Test (Aftertreatment)"

Probable Causes

Codes
Coolant level
Leaks
Connectors and Wiring
Sensor
Diverter valve

Recommended Actions

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Illustration 1	g06101393
(1) Aftertreatment #1 DEF pump #1 (2) Aftertreatment #1 DEF pump #2 (3) Aftertreatment #2 DEF pump #1 (4) Aftertreatment #2 DEF pump #2 (5) Aftertreatment #1 DEF pump #2 header (6) Aftertreatment #1 DEF pump #2 electrical connector (7) Aftertreatment #1 DEF pump #2 coolant diverter (8) Aftertreatment #1 DEF pump #1 coolant diverter (9) Aftertreatment #1 DEF pump #1 electrical connector (10) Aftertreatment #1 DEF pump #1 header (11) Aftertreatment #2 DEF pump #2 header (12) Aftertreatment #2 DEF pump #2 electrical connector (13) Aftertreatment #2 DEF pump #1 electrical connector (14) Aftertreatment #2 DEF pump #2 coolant diverter (15) Aftertreatment #2 DEF pump #1 coolant diverter (16) Aftertreatment #2 DEF pump #1 header

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Table 3
Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Connect to Cat^® Electronic Technician (ET) to the service tool connector. B. 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. Check the Coolant Level A. Determine if the engine coolant level is full.	Coolant Level	Result: The coolant level is OK. Proceed to Test Step 3. Result: The coolant level is NOT OK. Repair: Add coolant. Determine the cause of low coolant level. Refer to Troubleshooting, "Coolant Level Is Low" for additional information. If the problem is not resolved, proceed to Test Step 3.
3. Check for Coolant Leaks A. Check the entire engine cooling system for signs of coolant leaks. B. Inspect the coolant supply and return lines to the Pump Electronic Tank Unit (PETU) for leaks or damage that may cause restrictions. C. Remove the top cover to the PETU assembly to gain access to the coolant lines on the PETU. D. Inspect the coolant lines and routing inside the PETU assembly for leaks or damage that may cause restriction.	Leaks	Result: No leaks were detected. Proceed to Test Step 4. Result: There were leaks or damaged lines detected. Repair: Repair the leaks or damaged lines and refill the coolant system. Proceed to Test Step 4.
4. Inspect the Electrical Connectors and the Wiring A. Inspect the electrical connections to each of the DEF tank headers. Refer to Troubleshooting, "Electrical Connectors - Inspect" for additional information. B. Look for corrosion or loose wires.	Connectors and Wiring	Result: The connectors and wiring appear to be OK. Proceed to Test Step 5. Result: There is a problem with the connectors and/or wiring. Repair: Repair or replace the connectors or wiring. Ensure that all the seals are properly in place and ensure that the connectors are coupled. If the problem is not resolved, proceed to Test Step 5.
5. Check the Coolant Temperature Sensor A. Start the engine. B. Run the engine until normal operating temperature is reached. C. Connect to Cat ET. D. Use Cat ET to monitor the following temperature: - Coolant temperature Note: The temperature should be greater than 50° C (122° F).	Sensor	Result: The coolant temperature is greater than 50° C (122° F). Proceed to Test Step 6. Result: The coolant temperature is not greater than 50° C (122° F). Refer to Troubleshooting, "Coolant Temperature Is Low" for additional information. If the problem is not resolved, proceed to Test Step 6.
6. Check the DEF Coolant Diverter Valve Operation A. Turn the keyswitch to ON. B. Start the engine. C. Run the engine until normal operating temperature is reached. D. Connect to Cat ET. E. Select the appropriate "Diesel Exhaust Fluid Controller". F. Use Cat ET to set the status of the coolant diverter valve to Open using the "DEF Coolant Diverter Valve Solenoid Override". G. Feel the coolant hoses on the inlet and the outlet of the affected coolant diverter valve to make sure that there is coolant flowing through the PETU assembly. The lines on both sides of the coolant diverter valve should be warm to the touch.	Diverter Valve	Result: The coolant was flowing through the coolant diverter valve. Repair: Replace the DEF pump. Verify that the repair eliminated the problem. Result: The coolant was not flowing through the coolant diverter valve. Result: A failed coolant diverter valve has been detected. Replace the coolant diverter valve. 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).