0331930 JOHNSON LINK, Follower

Table 1
Event Code
Code and Description Conditions which Generate this Code System Response
E021(2) High Exhaust Temperature Derate The exhaust temperature has exceeded the trip point and the delay time has expired. Engine power is derated. The code is logged.
E173(1) High Exhaust Temperature Warning The alarm output is activated. The code is logged. Probable Causes
Diagnostic codes
Air inlet and exhaust system
Fuel injectors
Aftercooler (if applicable)
Exhaust temperature sensorRecommended Actions
Table 2
Troubleshooting Test Steps Values Results
1. Check for Diagnostic Codes
A. Establish communication between Caterpillar Electronic Technician (ET) and the ECM . Refer to Troubleshooting, "Electronic Service Tools" , if necessary.
B. Determine if a code is active or logged.
Diagnostic codes
Result: A diagnostic code is active or logged.
Troubleshoot the code. Refer to Troubleshooting, "Diagnostic Trouble Codes" in order to troubleshoot the associated diagnostic code.
Result: A diagnostic code is not active or logged.
Proceed to Test Step 2.
2. Air Inlet and Exhaust System
A. 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.
Restrictions and/or leaks
Results: There are no restrictions or leaks in the air inlet and exhaust system.
Proceed to Test Step 3.
Results: There are restrictions or leaks in the air inlet and exhaust system.
Repair the air inlet and exhaust system of leaks or restrictions.
3. Fuel Injectors
Note: If service has been performed on the engine fuel system recently, verify that the injector trim files are correct. Use Cat ET to check that the injector trim files are correct for the injectors that are installed on the engine.
A. Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.
B. Access the "Cylinder Cutout Test" in the "Diagnostic Tests" under the "Diagnostics" menu.
C. Perform the "Automatic Cylinder Cutout Test" on Cat ET.
Injector Solenoid Test
Result: The test was successful.
Return the unit to service.
Result: The test was not successful.
Diagnose the problem and then repair the problem.
Reset all active codes and clear all logged codes.
Verify that the repair eliminated the problem.
4. Aftercooler
A. Normal intake manifold pressure with high exhaust temperature can be caused by blockage in the aftercooler.
B. If the application has an aftercooler, check the aftercooler for correct operation. Check for blockage in the cores of the aftercooler.
Aftercooler
Result: The aftercooler does not have a blockage.
Proceed to Test Step 5.
Result: The aftercooler has a blockage.
Repair the blockage.
5. Exhaust Temperature Sensor
A. Use Cat ET to check the status of the exhaust temperature.
B. Use Cat ET to monitor the status of the exhaust temperature while the engine is warming to operating temperature.
C. Ensure that the reading that is displayed is reasonable. If an electronic problem with the sensor is suspected, refer to Troubleshooting, "Sensor Signal (PWM) - Test" for information that is related to troubleshooting the circuit that is for the exhaust temperature sensor.
Exhaust Temperature
Result: Exhaust temperature sensor is OK.
Return to Service.
Result: Exhaust temperature sensor NOT OK.
Replace the exhaust temperature sensor.