Case IH F-4076-00 - ECU – Engine Control Unit (ECU): Engine coolant temperature sensor voltage is higher than expected (Signal Above Range Max)

The control module is receiving a voltage signal from the engine coolant temperature sensor that exceeds the maximum allowable threshold. This usually points to an open circuit in the sensor wiring, a short circuit to a battery/power source, or a completely failed sensor with an internal open.

• MAGNUM AFS Connect
• Magnum 235–340 Series 4
• Steiger series (350–600 HP)
• Puma models
• Case IH 240 Series Combines (5140, 6140, 7140)
• Case skid steers
• Case compact track loaders
• Case backhoes

1. 1

   Verify cooling system integrity for an actual over-temperature condition, checking for leaks, physical damage, or blockages in the radiator.

2. 2

   Check system voltage by running the engine at 2000 RPM and monitoring battery voltage to ensure the alternator is not overcharging (which causes high voltage spikes).

3. 3

   Inspect the coolant temperature sensor harness connector for corrosion, pushed-out pins, or moisture.

4. 4

   Test the sensor signal wire with a multimeter for continuity back to the ECU, and verify it is not shorted to a 12V power source.

1. 1

   Safety First

   Turn off the machine, remove the key, and disconnect the negative battery cable. Allow the engine to cool completely to prevent severe burns from hot coolant.

2. 2

   Locate the Sensor

   Locate the engine coolant temperature sensor, typically threaded into the engine block near the thermostat housing or cylinder head.

3. 3

   Prepare for Coolant Loss

   Place a drain pan under the sensor area. You can either drain the coolant level below the sensor port or prepare the new sensor with thread sealant (if not pre-applied) to quickly swap them and minimize coolant loss.

4. 4

   Remove the Sensor

   Unplug the electrical connector and use a deep socket or wrench to unthread the defective sensor.

5. 5

   Install the New Sensor

   Thread the new sensor into the port and tighten it to the OEM torque specification.

6. 6

   Reconnect

   Plug the electrical connector back into the sensor until it clicks.

7. 7

   Refill Coolant

   Top off the engine coolant reservoir with the manufacturer-approved coolant to replace any lost fluid.

8. 8

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use a diagnostic service tool (like the CNH EST) to clear the F-4076-00 / 3007 fault code. Start the engine and verify the temperature gauge reads correctly without throwing an active code.