John Deere 111.18 – ECU: Engine Coolant Level Switch Shows Low Coolant Level

This code is triggered when the engine coolant drops below the safe threshold of the loss switch while the engine is operating at moderate temperatures (typically greater than 60°C / 140°F).

• 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
• 5E Series
• 5M Series
• 6M Series
• 6R Series
• 7R Series
• 8R Series
• 8RT Series
• 8RX Series
• 9R Series
• 850K
• 1050K
• 260E
• 370E
• 460E
• 130G
• 210G
• 7760
• WTS Combines

1. 1

   Visually inspect the coolant level in the header tank/reservoir to confirm if it is actually low

2. 2

   If the coolant is low (genuine leak cause): Inspect the entire cooling system for leaks, including the radiator, hoses, water pump seals, and head gasket

3. 3

   If the coolant level is full (sensor/wiring cause): Check the sensor's electrical connector and wiring harness for corrosion, damage, or short circuits

1. 1

   Cool Down

   Turn off the engine and allow it to cool completely to avoid burns from pressurized, hot coolant.

2. 2

   Top Up (If Applicable)

   If the coolant is simply low, fill the coolant to the maximum line and monitor the machine for leaks. If the code clears, no further repair is needed.

3. 3

   Drain Coolant (If replacing sensor)

   If the sensor is faulty, drain the coolant reservoir below the level of the sensor to prevent spilling.

4. 4

   Remove the Faulty Sensor

   Disconnect the electrical harness from the coolant level switch/sensor. Unthread or unclip the old sensor from the reservoir.

5. 5

   Install the New Sensor

   Install the replacement sensor into the tank and reconnect the electrical harness.

6. 6

   Refill and Test

   Refill the coolant to the proper level. Turn the ignition key on. In many cases, the code will resolve itself upon startup, or you may need to clear the DTCs via the CommandCenter display or a diagnostic scan tool.