John Deere 110.17 – Engine Control Unit (ECU): Engine Coolant Temperature Low

The engine coolant temperature does not reach the expected operational range, indicating it remains unusually low. The underlying condition usually points to a stuck-open thermostat, excessive coolant volume, inadequate engine load, or a faulty coolant temperature sensor.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8130
• 8230
• 8330
• 8430
• 8530
• 9230
• 9330
• 9430
• 9530
• 9630
• 7760
• 200CLC
• 310G

1. 1

   Operator 5-Minute Check: Perform a quick visual inspection of the cooling system. Check the coolant level to ensure the mixture and levels are correct, and inspect the radiator for any debris.

2. 2

   Engine Load Test: Warm up the engine and adjust the engine load settings. Sometimes the engine is simply not being sufficiently challenged to reach optimal operating temperatures.

3. 3

   Thermostat Inspection: Check if the engine thermostat is stuck in the open position, which would cause the engine to over-cool.

4. 4

   Sensor & Wiring Check: If the engine is genuinely running at normal temperatures but the code still appears, inspect the coolant temperature sensor and its wiring harness for damage or faults.

1. 1

   Warm Up the Engine

   Start the machine and apply a working load to warm up the engine. If the code clears, the issue was likely inadequate engine load.

2. 2

   Clean the Cooling System

   If the code persists, inspect and clean the radiator of any external debris or internal scale.

3. 3

   Replace the Thermostat

   If the engine still fails to reach operating temperature, access the thermostat housing. If the thermostat is stuck open, remove and replace it with a new OEM thermostat.

4. 4

   Replace the Coolant Temperature Sensor

   If the physical cooling system is functioning perfectly and the engine is warm, the sensor has likely failed. Disconnect the wiring harness, unthread the old sensor, and install a replacement sensor.

5. 5

   Reset the ECU

   After addressing the mechanical or electrical issue, cycle the key switch or use a diagnostic tool to reset the ECU and clear the stored codes. This ensures the ECU accurately monitors the engine temperature going forward. If the code returns, contact a John Deere dealer for advanced diagnostics.