Iveco 135 – Engine Control Unit (ECU): Temperature Sensor Circuit Malfunction of fuel

The engine control module has detected an irregular voltage or resistance reading from the fuel temperature sensor (e.g., an open circuit, short circuit, or out-of-range temperature reading like -20°C when the engine is warm).

• Iveco Daily
• Iveco Stralis
• Iveco Eurocargo

1. 1

   Use an Iveco-compatible diagnostic scanner (like EASY) to read live data for the fuel temperature and check for impossible default values (e.g., extreme negative temperatures).

2. 2

   Inspect the wiring harness leading to the fuel temperature sensor for chafed wires, melted insulation, or a loose 2-pin/3-pin connector.

3. 3

   Disconnect the sensor, turn the ignition to the ON position, and use a multimeter to verify that the ECU is supplying a standard 5V reference voltage to the connector.

4. 4

   Measure the resistance across the sensor's pins with a multimeter to check for an open circuit (infinite resistance) or a dead short, indicating internal failure.

1. 1

   Locate the Sensor

   Identify the fuel temperature sensor. Depending on the engine model, it is typically threaded into the fuel filter housing, the fuel rail, or the low-pressure fuel supply line.

2. 2

   Prepare the Area

   Turn off the ignition and disconnect the negative battery terminal. Place a shop rag or small catch pan beneath the sensor to catch any residual diesel fuel that may leak out.

3. 3

   Disconnect Wiring

   Press the release tab on the electrical connector and pull it free from the sensor.

4. 4

   Remove the Sensor

   Using the appropriate spanner (often a 17mm wrench for M14x1.5 threaded sensors), carefully unscrew the faulty sensor from its housing.

5. 5

   Install the New Sensor

   Thread the new OEM sensor into the housing by hand to prevent cross-threading. Tighten it securely with the spanner (do not over-tighten, as the housing may be plastic or cast alloy).

6. 6

   Reconnect

   Push the electrical connector onto the new sensor until it clicks into place.

7. 7

   Clear Codes and Test

   Reconnect the battery. Turn the ignition on and use your diagnostic tool to clear the 0135 fault code. Start the engine, check for any diesel leaks around the sensor threads, and verify that the check engine light remains off.