Iveco 232 – Engine Control Unit (ECU) / EDC: Coolant temperature sensor signal is out of range

The engine's control module is receiving a voltage or resistance reading from the coolant temperature sensor (CTS) that falls outside of the expected operating parameters (e.g., reading an impossible temperature like -40°C or +150°C). This is typically caused by a faulty sensor, a wiring short/open circuit, or a poor connection.

• Iveco Daily
• Iveco Stralis
• Iveco Eurocargo
• Iveco Trakker
• Iveco Tector engines
• Iveco Cursor engines (310-560 hp)

1. 1

   Check the physical coolant level to ensure the engine is not genuinely overheating or lacking coolant.

2. 2

   Inspect the sensor's electrical connector (usually a 2-pin or 3-pin sealed connector) for corrosion, water ingress, or loose pins.

3. 3

   Inspect the wiring harness leading to the sensor for chafing, pinched wires, or breaks. Verify continuity back to the ECU pins.

4. 4

   Verify the 5V reference voltage supply from the ECU to the sensor using a multimeter.

5. 5

   Test the sensor's resistance. Compare the resistance readings at ambient temperature against OEM specifications (resistance should drop as temperature increases).

6. 6

   Use a diagnostic scan tool to view live data. If the temperature reads a static extreme (like -40°C), it usually indicates an open circuit or unplugged sensor.

1. 1

   Turn off the ignition and disconnect the negative battery terminal.

   Ensure the vehicle is powered down before beginning work.

2. 2

   Locate the coolant temperature sensor.

   It is typically mounted in the coolant pipe, cylinder head, or thermostat housing.

3. 3

   Place a drain pan underneath the sensor location.

   This will catch any coolant that escapes during removal.

4. 4

   Disconnect the electrical wiring harness from the sensor.

   Depress the locking tab to release the connector.

5. 5

   Unscrew the old sensor from the housing.

   Use a wrench or deep socket.

6. 6

   Clean the mating threads on the housing.

   Ensure the threads are free of debris for the new sensor.

7. 7

   Install the new sensor.

   Thread the new sensor into the housing by hand to prevent cross-threading, then tighten it to the manufacturer's specified torque.

8. 8

   Reconnect the electrical connector.

   Push it in until it clicks into place.

9. 9

   Top up the engine coolant.

   Fill to the correct level to replace any fluid lost during the swap.

10. 10

    Reconnect the battery and test.

    Start the engine, let it reach operating temperature, and check for coolant leaks around the new sensor.

11. 11

    Clear the fault code and verify.

    Use an OBD diagnostic tool to clear the 0232 fault code and verify that the dashboard temperature gauge is reading correctly.