Iveco 602 – Engine Control Unit (ECU) / EDC (Electronic Diesel Control): Faulty oxygen sensor heater circuit 1

The control module has detected a malfunction—such as an open circuit, a short circuit to ground, or out-of-range resistance—specifically in the heater circuit of Sensor 1 (the upstream sensor located before the catalytic converter or SCR system).

• Iveco Daily
• Iveco Stralis
• Iveco Tector

1. 1

   Scan and Save Data: Use a diagnostic tool to read all stored codes and freeze-frame data. Verify if the code is active or stored.

2. 2

   Visual Inspection: Locate Sensor 1 (upstream of the catalytic converter/SCR). Inspect the sensor's wiring harness and connector for melted wires, chafing, corrosion, or loose pins. Exhaust heat frequently damages these harnesses.

3. 3

   Check Power and Ground: Disconnect the sensor. Turn the ignition ON and use a multimeter to verify that the heater circuit is receiving battery voltage (usually 12V or 24V depending on the vehicle system) and has a good ground.

4. 4

   Test Sensor Resistance: Measure the resistance across the heater pins on the sensor itself. If the multimeter reads an open circuit (infinite resistance) or a dead short, the internal heating element has failed, and the sensor must be replaced.

1. 1

   Prep the Vehicle

   Disconnect the vehicle's battery to prevent accidental short circuits. Ensure the exhaust system has cooled down to avoid burns.

2. 2

   Disconnect the Sensor

   Unplug the electrical connector for the upstream oxygen sensor (Sensor 1).

3. 3

   Remove the Old Sensor

   If the sensor is seized in the exhaust pipe, apply penetrating oil to the threads and let it soak. Use a dedicated oxygen sensor socket or a wrench to carefully unscrew it.

4. 4

   Prepare the New Sensor

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (Note: Many premium OEM/aftermarket sensors come with pre-greased threads). Caution: Do not get any anti-seize on the sensor tip, as this will contaminate it.

5. 5

   Install the New Sensor

   Thread the new sensor in by hand to prevent cross-threading. Tighten it to the manufacturer's specified torque.

6. 6

   Reconnect Wiring

   Plug the electrical connector back in. Ensure the wiring harness is secured and routed safely away from the hot exhaust pipe.

7. 7

   Clear Codes

   Reconnect the battery, connect your diagnostic scanner, and clear the 0602 fault code.

8. 8

   Test Drive

   Start the engine and monitor the live data for Sensor 1 to ensure the heater circuit activates and the sensor begins reading exhaust gases properly.