SPRING 4T4027 - Caterpillar

Use this procedure in order to troubleshoot a high exhaust temperature or use this procedure if one of the following event codes is active. Refer to Troubleshooting, "Event Codes" for information about event codes and the default trip points for these codes. You must access the monitoring system on Caterpillar Electronic Technician (ET) in order to view the current trip points for these codes.
Table 1
Event Code
Code and Description Conditions which Generate this Code System Response
E173(1) High Exhaust Temperature Warning The exhaust temperature is above the trip point temperature. The code is logged.
E021(2) High Exhaust Temperature Derate The engine is derated. The code is logged. Probable Causes
Diagnostic codes
Excessive load
Air inlet and exhaust system
Fuel injectors
Aftercooler (if applicable)Recommended Actions
Diagnostic Codes
Connect Cat ET and check for active and/or logged diagnostic codes. Troubleshoot any active diagnostic codes before continuing with this procedure.Excessive Load
Ensure that the load is not excessive. If necessary, reduce the load. When possible, avoid unnecessary overloads and/or extended overloads.Air Inlet and Exhaust System
Check for air inlet restrictions and/or leaks. A one degree increase in the inlet manifold temperature will increase the exhaust temperature by approximately three degrees. Check for leaks between the exhaust manifold and the turbocharger. Check for exhaust restrictions. Refer to the Systems Operation/Testing and Adjusting manual for more information on inspecting the air inlet and exhaust system.Fuel Injectors
Faulty injectors that deliver too much fuel will increase exhaust temperatures. Connect Cat ET in order to determine if any diagnostic codes for the injector solenoids are present. Perform the "Injector Solenoid Test". Observe that the injector solenoids are being energized on Cat ET. Perform the "Cylinder Cutout Test". Locate the misfiring cylinder. Refer to Troubleshooting, "Injector Solenoid - Test".Aftercooler (if applicable)
Normal intake manifold pressure with high exhaust temperature can be caused by blockage of the fins of the aftercooler core.If the application has an aftercooler, check the aftercooler for correct operation. Check for blockage in the cores of the aftercooler.