Iveco 2.1 – Engine ECU / EDC (Electronic Diesel Control): Coolant Temperature Sensor Circuit Malfunction

The system has detected that the Coolant Temperature Sensor is defective, short-circuited (to ground or positive), or open-circuited. The EDC warning light may remain OFF or blink, and the system applies a default substitution value (typically 0ºC). Symptoms include longer cranking/starting times when the engine is cold, increased engine noise due to a high fuel injection advance, and complete loss of engine overheating protection strategies.

• Iveco Daily
• Iveco Eurocargo
• Iveco Stralis
• Iveco Trakker
• Iveco Eurotrakker
• Iveco Bus and coach platforms

1. 1

   Read Live Data: Connect a diagnostic tool and read the live coolant temperature parameters. If the reading is locked at a substitution value (like 0ºC or 15-19ºC when the dash gauge reads 90ºC), the fault is confirmed.

2. 2

   Visual Inspection: Inspect the sensor connector and wiring harness for corrosion, chafing, or broken wires.

3. 3

   Continuity Testing: Disconnect the sensor and the EDC harness. Check for continuity between the sensor connector pins and the corresponding EDC pins (e.g., pins 57 and 58, or 41 and 58, depending on your specific EDC wiring diagram).

4. 4

   Resistance Testing: Measure the resistance of the sensor itself with a multimeter and compare it against standard Iveco temperature-resistance curves. If it reads completely open (infinite resistance) or shorted (zero resistance), the sensor is dead.

1. 1

   Preparation

   Ensure the engine is completely cool to prevent severe burns and to ensure the cooling system is depressurized.

2. 2

   Battery Disconnect

   Disconnect the negative terminal of the battery to protect the EDC.

3. 3

   Locate the Sensor

   The coolant temperature sensor is typically located near the thermostat housing, on the radiator, or threaded directly into the engine block.

4. 4

   Disconnect Wiring

   Unplug the electrical connector from the sensor.

5. 5

   Remove the Sensor

   Using a properly sized socket wrench, carefully unscrew the old sensor. Have a rag or catch pan ready, as a small amount of coolant will leak out.

6. 6

   Install the New Sensor

   Apply a thread sealant to the threads of the new sensor (if it does not come with a pre-applied sealant or a crush washer). Thread it in by hand to prevent cross-threading, then tighten to the manufacturer's torque specification.

7. 7

   Reassembly

   Reconnect the electrical connector and the battery.

8. 8

   Fluid Check

   Top up the coolant reservoir to replace any fluid lost during the swap.

9. 9

   Final Testing

   Start the engine, check the sensor area for coolant leaks, and use a diagnostic tool to clear the EDC fault codes.