FAN 4543411 - Caterpillar

Probable Causes
Diagnostic codes
Misreading of fuel level
Fuel leakage
Fuel quality
Quality of oil
Low engine temperature
Prolonged operation at idle speed
Engine operating speed
Air intake and exhaust system
Aftertreatment Regeneration Device (ARD)
Cooling fan
Reduced pressure of intake air
Excessive valve lash
Failure of the primary speed/timing sensorRecommended Actions
Diagnostic Codes
Use one of the following methods to check for active diagnostic codes:
The electronic service tool
The display on the control panelElectronic Service Tool
Connect the electronic service tool to the diagnostic connector.
Check for active diagnostic codes on the electronic service tool.
Investigate any active codes before continuing with this procedure. Refer to Troubleshooting, "Troubleshooting with a Diagnostic Code".Display on the Control PanelNote: The following procedure is only applicable if the application is equipped with a display on the control panel.
Check the display on the control panel for active diagnostic codes.
Troubleshoot any active codes before continuing with this procedure. Refer to Troubleshooting, "Troubleshooting with a Diagnostic Code".Misreading of Fuel Level
Monitor the fuel consumption over a period of 50 engine hours. If the fuel consumption is excessive, perform the following procedure.Fuel Leakage
Check for evidence of fuel leaks on the engine. Rectify any leaks.Fuel Quality
The quality of the fuel that is used in the engine will affect the rate of fuel consumption. Refer to "General Fuel Information" in the Operation and Maintenance Manual, "Refill Capacities".
If the fuel is not of an acceptable quality, drain the fuel system and replace the fuel filters. Refill the fuel system with fuel of an acceptable quality. Refer to the applicable sections in the Operation and Maintenance Manual.
If the fuel is of an acceptable quality, refer to "Quality of Oil".Quality of Oil
The nominal viscosity of the lubricating oil that is used in the engine will affect the rate of fuel consumption. The viscosity of lubricating oil is defined by the SAE grade of the lubricating oil. The grade of the lubricating oil must be correct for the ambient conditions. Lubricating oil for high ambient temperatures will affect fuel consumption in cold ambient temperatures. Refer to "Engine Oil" in the Operation and Maintenance Manual, "Refill Capacities".
The actual viscosity of the lubricating oil that is used in the engine will change throughout the service life of the oil. Lubricating oil that is heavily contaminated will have a negative effect upon the rate of fuel consumption.
If the quality of the oil is unacceptable or if the oil has exceeded the service life, drain the oil system and replace the oil filter. Refill the oil system with oil of an acceptable quality. Refer to the applicable sections in the Operation and Maintenance Manual.
If the oil is of an acceptable quality, refer to "Low Engine Temperature".Low Engine Temperature
The operating temperature of the engine will affect the rate of fuel consumption. Operation of the engine below the correct temperature will increase fuel consumption. Failure of the water temperature regulator can prevent the engine from operating at the correct temperature.
If the engine operating temperature is low, check the operation of the water temperature regulator. If the water temperature regulator does not operate correctly, a new water temperature regulator