New Holland ENG 146 – ENGINE Controller (Engine ECU): Coolant Temperature level has exceeded the warning limit.

The engine is overheating. The coolant temperature sensor is reading a temperature that has surpassed the safe operating threshold programmed into the system, triggering an engine protection mode.

• T4
• T5
• T7
• TM Series
• TM120
• TM130
• TM140
• TM155
• TM175
• TM190
• TC Series
• Boomer
• Workmaster series
• Backhoes
• skid steer loaders
• telehandlers
• excavators

1. 1

   Visual Airflow Inspection (Most Common): Check the radiator, cooling stack, and screens for blockages caused by dirt, dust, and chaff.

2. 2

   Coolant Level & Condition: Once the engine is cool, check the overflow tank and radiator for proper coolant levels and signs of contamination (e.g., oil in the coolant).

3. 3

   Thermostat Check: Feel the upper and lower radiator hoses. If the engine is overheating but the hoses are completely cool to the touch, the thermostat is likely stuck closed.

4. 4

   Fan Operation: Inspect the viscous fan clutch or electric fan logic to ensure the fan is engaging properly under load.

5. 5

   Sensor Accuracy: Use a diagnostic tool to verify the actual coolant temperature reading against a manual temperature probe. If the engine is physically cool but the ECU reads it as overheating, the sensor has failed.

6. 6

   Hydraulic/PTO Load: Ensure the machine isn't overheating strictly due to hydraulic overload or a stuck valve causing excessive engine drag.

1. 1

   Clean radiator fins and screens

   If the Radiator is Blocked: Use compressed air to blow out the radiator fins and screens.

2. 2

   Separate and clean coolers

   If heavily packed, separate the coolers in the cooling stack to clean trapped debris thoroughly.

3. 3

   Drain engine coolant

   If the Thermostat is Faulty: Drain the engine coolant into a clean drain pan.

4. 4

   Remove thermostat housing

   Unbolt and remove the thermostat housing.

5. 5

   Remove old thermostat

   Remove the old thermostat and scrape away any old gasket material.

6. 6

   Install new thermostat

   Install the new thermostat (typically rated for 180°F / 82°C) and a new gasket.

7. 7

   Reattach housing

   Reattach the housing and torque the bolts to OEM specifications.

8. 8

   Locate coolant temperature sensor

   If the Coolant Temperature Sensor is Faulty: Locate the sensor on the engine block or thermostat housing.

9. 9

   Disconnect wiring harness

   Disconnect the 2-pin wiring harness.

10. 10

    Unscrew old sensor

    Unscrew the old sensor (have the new one ready to minimize coolant loss if you haven't drained the system).

11. 11

    Install new sensor

    Thread in the new sensor (e.g., 1/2" x 14 NPTF thread) and tighten.

12. 12

    Reconnect wiring harness

    Reconnect the wiring harness.

13. 13

    Refill cooling system

    Final Steps: Refill the system with the OEM-specified coolant mixture.

14. 14

    Bleed cooling system

    Bleed the cooling system to remove any trapped air pockets.

15. 15

    Verify repair under load

    Run the tractor under load to verify the temperature stabilizes and the ENG 146 code clears.