Iveco 132 – Engine Control Unit (ECU): Incorrect signal circuit coolant temperature sensor

The engine control system is receiving an implausible, out-of-range, or missing voltage signal from the engine coolant temperature sensor, usually pointing to a failed sensor, a wiring short, or an open circuit.

• Iveco Daily
• Iveco Stralis
• Iveco Trakker
• Iveco Eurocargo
• Iveco PowerStar
• FPT / Iveco Motors

1. 1

   Inspect the coolant temperature sensor and its electrical connector for corrosion, backed-out pins, or physical damage.

2. 2

   Check the wiring harness between the sensor and the Engine ECU for open circuits, short circuits to ground, or short circuits to battery voltage.

3. 3

   Use a multimeter to verify the sensor's internal resistance to check for an internal short or open circuit.

4. 4

   Verify the on-board network voltage, as voltage drops from terminal '15' or out-of-range system voltage can trigger cascading sensor faults.

1. 1

   Power Down

   Shut the engine down and keep the key switch in the 'OFF' position for at least 15 seconds to allow the ECU to power down safely. Disconnect the vehicle's negative battery terminal.

2. 2

   Locate the Sensor

   Locate the coolant temperature sensor on the engine (typically mounted on the thermostat housing or engine block water jacket).

3. 3

   Drain Coolant

   Partially drain the cooling system to a level below the sensor to prevent coolant spillage during removal.

4. 4

   Remove the Sensor

   Disconnect the electrical connector plug. Unscrew and remove the faulty coolant temperature sensor.

5. 5

   Install the New Sensor

   Thread the new sensor (ensure any required sealing washer or O-ring is in place) and tighten to the manufacturer's specified torque. Reconnect the electrical harness plug.

6. 6

   Refill and Bleed

   Refill the engine coolant to the correct level and bleed the cooling system of any trapped air.

7. 7

   Clear the Fault Code

   Reconnect the battery. Use an Iveco diagnostic tool (such as EASY, Jaltest, or a compatible OBD scanner) to erase the error memory.