HARNESS AS-ENGINE 4198895 - Caterpillar

Probable Causes
High ambient air temperature
High coolant temperature
High inlet air restriction and/or high altitude
Faulty inlet air temperature sensor and/or circuit
Insufficient flow of cooling water through the aftercooler
Insufficient flow of air through the aftercoolerRecommended Actions
High Ambient Air Temperature
Determine if the ambient air temperature is within the design specifications for the cooling system.Determine the cause of the high ambient air temperature. Correct the problem.High Coolant Temperature
Check the engine for a coolant temperature that is excessive. Refer to Troubleshooting, "Engine Coolant Temperature (High)".High Inlet Air Restriction and/or High Altitude
When inlet air pressure is low, the turbocharger works harder in order to achieve the desired inlet air pressure. This increases inlet air temperature.Measure the inlet air pressure while the engine is operating under load. For specific data, refer to the data from Technical Marketing Information (TMI) for the engine.Inlet Air Restriction
Check for plugged air filters. Check for obstructions to the air inlet. Replace the air filters and/or remove the obstruction from the air inlet.High Altitude
Ensure that the settings for the engine are correct for the altitude.Faulty Inlet Air Temperature Sensor and/or Circuit
Allow the inlet air temperature sensor to cool and remove the sensor from the engine. Check the reading for the inlet air temperature. If the sensor is OK, the temperature from the sensor and the ambient temperature will be approximately equal.If the temperatures do not agree, replace the sensor with a sensor that is known to be good. Verify that the problem is solved.Insufficient flow of cooling water through the aftercooler
Check the temperature of the coolant at the inlet of the aftercooler. Compare the reading to the regulated temperature. If the temperature is OK, check the temperature of the coolant at the outlet of the aftercooler. A high temperature differential indicates an insufficient flow rate.If there is a high differential between the inlet temperature and the outlet temperature of the coolant at the aftercooler, check for the following problems:
Obstructions in the coolant circuit of the aftercooler
Failure of the coolant pumpRepair any problems that are found.Insufficient Flow of Air Through the Aftercooler
Determine the pressure differential of the inlet air across the aftercooler. For specific data, refer to the data from TMI for the engine.If the pressure differential of the air across the aftercooler does not match the specifications, clean the aftercooler.