John Deere 109.31 – Engine Control Unit (ECU): Coolant Pressure Signal Fault Detected

The engine coolant pressure is low or the signal is reading slightly/extremely low. The system flags this when the coolant pressure drops below the acceptable operating range, which can lead to engine power limitation to prevent overheating.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 7R Series
• 8310RT
• 8335RT
• 8360RT
• 7810 IVT
• 8210T
• 7180
• 7280
• 7380
• 7480
• 7580
• 7780
• 7980
• 8100-8600
• S650
• S660
• S670
• S680
• S690
• 7760
• PowerTech 9.0L
• PowerTech 10.5L
• PowerTech 12.5L

1. 1

   Review historical data to see the frequency and circumstances of the low-pressure readings

2. 2

   Verify that the engine coolant level is not low

3. 3

   Check the radiator sealed lid/pressure cap for damage or a failed seal

4. 4

   Perform a detailed visual inspection of the entire cooling system to detect any leaks

5. 5

   Check the coolant pressure sensor and its wiring harness for intermittent connection issues or physical damage

1. 1

   Cycle Power

   Turn the ignition key off and back on. In some cases, the code can be resolved simply by cycling the tractor's power.

2. 2

   Top Up Coolant

   If the coolant level is found to be low, fill the coolant to the appropriate level.

3. 3

   Replace Pressure Cap

   If the pressure cap is defective or failing to hold a seal, replace it.

4. 4

   Repair Leaks

   If leaks are found in the cooling system (hoses, radiator, etc.), repair or replace the affected components.

5. 5

   Replace Sensor

   If the system is full, holds pressure, and has no leaks, the coolant pressure sensor itself is likely failing and must be replaced.

6. 6

   Monitor System

   Clear the codes and monitor the coolant system closely during operation to ensure the repair was successful and pressure remains stable.