Cummins ISX11.9 CM2250 – Service Manual Coolant Temperature Below Normal

Electronic fault codes active or high counts of inactive fault codes

Refer to Section TF in the Fault Code Troubleshooting Manual, Bulletin 4022225.

Coolant temperature sensor is malfunctioning

Use an electronic service tool to check the coolant temperature sensor circuit. Refer to
Procedure 019-019 in Section 19
.

Coolant temperature gauge is malfunctioning

Test the temperature gauge. Repair or replace the gauge, if necessary. Contact a Cummins® Authorized Repair Location.

Engine is operating at low ambient temperature

Check the winterfront, shutters, and under-the-hood air. Use under-the-hood intake air in cold weather. Refer to Cold Weather Operation, Bulletin 3387266 and
Procedure 101-015 in Section 1 of the Operation and Maintenance Manual, ISX11.9 CM2250, Bulletin 2883444.

Fan drive or fan controls are malfunctioning

Check the fan drive and controls. Refer to
Procedure 008-027 in Section 8
.

Coolant fill line is not routed correctly

Check the routing of the coolant fill line. Refer to the OEM service manual.

Radiator shutters are stuck open or opening early

Check the shutter operation. Repair or replace the shutters if necessary. Refer to the OEM service manual and
Procedure 008-049 in Section 8.

Radiator swing check valve is malfunctioning (if equipped)

Check the swing check valve for correct operation. Refer to the OEM service manual.

Thermostat seal is damaged, missing, or not installed correctly

Check the thermostat seal. Check the thermostat for correct seating. Refer to Procedure 008-013 or
Procedure 008-016 in Section 8.

Thermostat is not correct or is malfunctioning

Check the thermostat for the correct part number and for correct operation. Refer to
Procedure 008-013 in Section 8
.

Coolant flow through the radiator is not correct

Check for correct coolant flow through the radiator. Refer to
Procedure 008-042 in Section 8
.