Iveco 149 – Engine Control Unit (ECU) / EDC: Fuel Heater Circuit Malfunction

The engine management system has detected an electrical anomaly in the circuit responsible for heating the diesel fuel filter. The underlying condition is typically an open circuit, a short circuit, or an over-temperature error at the ECM power stage.

• Iveco Daily
• Iveco Eurocargo
• Iveco Stralis
• UAZ Patriot

1. 1

   Inspect the wiring loom leading to the fuel filter heater for chafed cables, broken wires, exposed copper, or heat damage at the plug connector

2. 2

   Test the fuel heater control relay (often designated as Relay T19, T31, or 25810) and check the associated fuses in the engine bay fuse box

3. 3

   Test the load and output of the fuel heater element using a multimeter to check for an internal open or short circuit

4. 4

   Verify that the EDC is sending the correct voltage to the heater circuit when commanded via active diagnosis

1. 1

   Disconnect Power

   Before working on the EDC system or electrical components, disconnect the positive pole of the battery to prevent control unit damage.

2. 2

   Repair Wiring

   If the diagnostic checks revealed chafed or broken wires, repair them using silver solder and heat shrink, or proper crimps, to ensure correct sensor/heater readings. If the connector plug is melted, splice in a replacement pigtail connector and fit a heat protection sleeve.

3. 3

   Replace the Heater Element

   If the wiring and relays are intact but the heater element failed the multimeter test, locate the fuel filter housing. Disconnect the electrical connector, unbolt/unscrew the faulty fuel heater element from the filter housing, and install the new OEM replacement part.

4. 4

   Clear Fault Codes

   Reconnect the battery. Clear the fault codes using an Iveco diagnostic tool (like Modus or IWT). Alternatively, use the manual EDC blink code deletion procedure: With the key turned off, press and hold the diagnosis button. Keeping the button pressed, turn the ignition key on. Keep the button pressed for 5 seconds, then let go. Turn the key off.