SHOE (Master) 8S0391 - Caterpillar

Table 1
Event Code    
Code and Description    Conditions which Generate this Code    System Response    
E194(1) High Exhaust Temperature     The exhaust temperature that has been calculated by the Electronic Control Module (ECM) is above the trip point for the delay time.     The code is logged.    The ECM monitors the following parameters in order to calculate the exhaust temperature:
Intake manifold air temperature
Atmospheric pressure
Engine speedHigh intake manifold air temperature, high altitude operation, and high engine loads can cause the exhaust temperature to increase to a level that may damage the components of the exhaust system. If this occurs, the ECM may derate the engine in order to reduce the exhaust temperature. This protects the components of the exhaust system from damage.Probable Causes
Diagnostic codes
Engine/vehicle operating conditions
Air-to-Air Aftercooler (ATAAC)
Supply circuit for the atmospheric pressure sensor
Air inlet and exhaust systemRecommended Actions
Diagnostic Codes
Connect the Caterpillar Electronic Technician (ET) and check for active and/or logged diagnostic codes. Troubleshoot any active diagnostic codes before continuing with this procedure.Engine/Vehicle Operating Conditions
Interview the operator, when possible. Determine if the engine was under heavy load or the engine is operating at a high altitude.Correct any problems that have been discovered. If the event occurred because of normal engine operation, clear the logged event and return the engine to service.Air-to-Air Aftercooler (ATAAC)
The intake manifold air temperature can increase if the ATAAC is obstructed. Check the fins of the ATAAC for obstructions.If necessary, clean the debris from the fins of the ATAAC. Clear the event. Return the engine to service.Supply Circuit for the Atmospheric Pressure Sensor
If the atmospheric pressure sensor is not being powered by the 5 volt supply, the output of the sensor will float to a value that indicates a high barometric pressure. This is interpreted by the ECM as a high altitude condition. The ECM receives the erroneous value of altitude and the ECM derates the engine.Ensure that the keyswitch is in the ON position. Measure the value of the 5 volt supply at the harness connector for the atmospheric pressure sensor. If the 5 volt supply is not available at the harness connector, repair the circuit. Refer to Troubleshooting, "Sensor Supply - Test" for information.Air Inlet and Exhaust System
Check the air intake manifold (boost) pressure. Check for air inlet restrictions and/or leaks. Refer to Systems Operation/Testing and Adjusting.
Check for leaks between the exhaust manifold and the turbocharger. Check for exhaust restrictions. Refer to Systems Operation/Testing and Adjusting.