3176C, 3406E and 3456 Industrial Engines Troubleshooting – Intake Manifold Air Temperature Is High

Use this procedure in order to troubleshoot high inlet air temperature. Use this procedure if the following event code 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
105-0 High Inlet Air Manifold Temperature (Warning) The intake manifold air temperature is above the trip point for the delay time. The code is logged.
The diagnostic lamp will flash.
The alarm lamp will illuminate.

Probable Causes


  • High coolant temperature 
  • High ambient air temperature 
  • Air inlet restriction 
  • Exhaust restriction 
  • Altitude 
  • Engine Overload 

Recommended Actions

High Coolant Temperature

A high coolant temperature will increase the intake manifold air temperature.

Verify that the cooling system is filled to the proper level. If the coolant level is too low, air will get into the cooling system. Air in the cooling system will cause a reduction in coolant flow.

Check the operation of the cooling fan. A fan that is not turning at the correct speed can cause improper air speed across the aftercooler core. The lack of proper air flow across the aftercooler core can cause the intake air not to cool to the proper temperature.

Check for air in the cooling system. Air can enter the cooling system in different ways. The most common causes of air in the cooling system are the incorrect filling of the cooling system and combustion gas leakage into the cooling system. Combustion gas can get into the system through inside cracks, a damaged cylinder head, or a damaged cylinder head gasket.

High Ambient Air Temperature

Determine if the ambient air temperature is within the design specifications for the cooling system. When ambient temperatures are too high for the rating of the cooling system, there is not enough of a temperature difference between the ambient air and coolant temperatures.

Inlet Air Restriction

Check for a restriction in the air inlet system. A restriction of the air that is coming into the engine can cause high cylinder temperatures. High cylinder temperatures cause higher than normal temperatures in the cooling system. The coolant temperature must be within the correct range in order to cool the intake air.

Exhaust Restriction

Check for a restriction in the exhaust system. A restriction of the air that is coming out of the engine can cause high cylinder temperatures.


Consider high altitude operation. The cooling capability of the cooling system is reduced at higher altitudes. A pressurized cooling system that is large enough to keep the coolant from boiling must be used. Make sure that the settings for the engine are correct for the altitude.

Engine Overload

The engine may be running in the lug condition. When the load that is applied to the engine is too large, the engine will run in the lug condition. When the engine is running in the lug condition, engine rpm does not increase with an increase of fuel. This lower engine rpm causes a reduction in coolant flow through the system.

If an electrical problem is suspected with the sensor circuit, refer to Troubleshooting, “Sensor Signal (Analog, Active) – Test”.

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