JOINT GROUP 8D4667 - Caterpillar

Table 1
Event Code    
Code and Description    Conditions which Generate this Code    System Response    
E199(1) Low Coolant Temperature : least severe     The temperature of the engine coolant has fallen below the trip point for the programmed delay time.     The code is logged.
The ECM may derate the engine or shutdown the engine.    
E199(2) Low Coolant Temperature : moderate severity     The temperature of the engine coolant has fallen below the trip point for the programmed delay time.    
E199(3) Low Coolant Temperature : most severe     The temperature of the engine coolant has fallen below the trip point for the programmed delay time.    Note: Refer to Troubleshooting, "Engine Monitoring System" for information on trip points and delay times.Probable Causes
Faulty jacket water heater
Faulty coolant temperature sensor and/or circuit
Faulty water temperature regulatorsRecommended Repairs
Check the Jacket Water Heater (if applicable)
Determine if the jacket water heaters are functioning properly.If the jacket water heaters are not functioning properly, determine the cause of the malfunction of the heaters. Make the necessary repairs.Check the Engine Coolant Temperature Sensor and/or the Circuit
Check the reading of the engine coolant temperature with the Caterpillar Electronic Technician (ET). The temperature should rise steadily as the engine is warmed. Ensure that the temperature is reasonable.If the reading on Cat ET for the engine coolant temperature is not reasonable, troubleshoot the circuit for the engine coolant temperature sensor. Refer to Troubleshooting, "Sensor Signal (Analog, Passive) - Test".Check the Water Temperature Regulators
The water temperature regulators should not begin to open until jacket water reaches opening temperature for the regulators. Allow the engine to cool and then start the engine. Check the hose at the outlet for the jacket water. If the hose is warm and normal operating temperature is not achieved yet, a regulator may be stuck open.If the water temperature regulators are malfunctioning, check the water temperature regulators according to Systems Operation/Testing and Adjusting, "Testing the Cooling System". Replace the water temperature regulators, if necessary.