John Deere 110 – ECU: Engine Coolant Temperature Extremely High

The engine control system has detected that the engine coolant temperature has exceeded the maximum safe operating limit (typically above 115°C / 240°F). To protect the engine from catastrophic failure, the controller will actively derate engine power, disable power boost, and may eventually command an engine shut-off if the temperature does not drop.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5065M
• 5075M
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5095M
• 5095MH
• 5105M
• 5015ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 7220
• 7320
• 7420
• 7520
• 8120
• 8220
• 8320
• 8420
• 8520
• 9000 Series 4WD
• 9560
• 9660
• 9760
• 9860
• 333E
• 744H
• 744MH

1. 1

   Check the radiator and cooling system for external blockages caused by dirt, debris, or chaff (highly common during harvest or bush hogging).

2. 2

   Check the coolant level in the radiator/overflow tank. Inspect coolant lines for pinched hoses, and check for puddles under the tractor or wet spots around hose clamps and the water pump weep hole.

3. 3

   Inspect the fan belt for slipping or breakage. Check the fan clutch engagement (if the fan freewheels easily at all temperatures, the viscous coupling has failed).

4. 4

   Feel the upper radiator hose. If the gauge shows overheating but the upper hose is cool, the thermostat is likely stuck closed.

5. 5

   If the engine is genuinely running cool but the code persists, use a multimeter to test the coolant temperature sensor. The resistance should change smoothly as the temperature changes.

1. 1

   Immediate Action

   Stop the tractor or reduce the engine load immediately to allow the oil and coolant temperatures to drop. Do not shut the engine off instantly if it is boiling hot unless it is actively losing coolant; let it idle to circulate coolant, then shut it down.

2. 2

   Clean the Radiator

   Using compressed air or a pressure washer (carefully), clean the entire cooler stack from the engine side outward to remove debris.

3. 3

   Top Up Fluids

   Once the engine is cool, verify the radiator fill valve is closed and add 50/50 pre-mixed coolant to the proper level.

4. 4

   Replace Failing Mechanical Components

   If a leak is found, replace the damaged hose, clamp, or water pump. If the thermostat is stuck closed, drain the upper coolant, unbolt the thermostat housing, and install a new thermostat and gasket. If the fan clutch has failed, unbolt the fan assembly and replace the viscous clutch.

5. 5

   Replace the Sensor (If Applicable)

   If diagnostics prove the sensor is giving a false reading, disconnect the wiring harness, unthread the old sensor from the engine block/water jacket, install the new sensor, and clear the ECU codes.