Iveco 038B – Engine Control Unit (ECU): Open Throttle RRC state or increased exhaust gas temperature

This code indicates a malfunction in the Throttle Valve Actuator (TVA) circuit or its physical operation. The throttle valve is either stuck in the open position, has an open electrical circuit (wiring/connector failure), or is failing to create the necessary intake manifold vacuum to draw in exhaust gases, which consequently leads to elevated exhaust gas recirculation (EGR) temperatures.

• Iveco Daily
• Iveco Stralis
• Iveco Tector

1. 1

   Inspect the wiring harness and connector leading to the Throttle Valve Actuator (TVA) for breaks, chafing, or corrosion. The code explicitly flags an 'open circuit,' which often points to a disconnected plug or broken wire.

2. 2

   Remove the intake hose leading to the throttle body and inspect the throttle flap. Check if it is physically jammed open due to heavy carbon/soot buildup from the EGR system.

3. 3

   Clear the codes using a diagnostic scanner. If 038B returns immediately upon turning the key (without starting the engine), it is a hard electrical fault (wiring or dead actuator motor). If it returns only after driving, it is likely a mechanical binding or temperature-related issue.

4. 4

   Verify that the EGR valve itself is not stuck closed, as the TVA and EGR work in tandem and a failure here correlates with elevated exhaust gas temperatures.

1. 1

   Disconnect Power

   Disconnect the negative battery terminal to prevent electrical shorts and ECU damage.

2. 2

   Locate the TVA

   Locate the Throttle Valve Actuator on the intake manifold (usually at the front of the engine where the intercooler pipe meets the intake).

3. 3

   Remove Components

   Disconnect the electrical connector from the TVA. Loosen the hose clamp and remove the boost/intercooler hose from the throttle body.

4. 4

   Unbolt the Actuator

   Remove the retaining bolts securing the TVA to the intake manifold.

5. 5

   Clean the Intake

   Before installing the new part, inspect the intake manifold opening. Clean out any excessive carbon or oily sludge to prevent the new valve from sticking.

6. 6

   Install the New TVA

   Mount the new throttle valve actuator and torque the bolts to OEM specifications. Important Note for Iveco Daily F1A engines: If you are replacing an old-style TVA with a new-style TVA, you must install an OEM adaption cable (Part No. 504388760) for the wiring to connect properly.

7. 7

   Reassembly

   Reattach the intercooler hose and tighten the clamp. Reconnect the electrical plug.

8. 8

   Clear Codes

   Reconnect the battery, turn the ignition on, and use a diagnostic scanner to clear the 038B fault code from the EDC16C39 ECU. Perform a test drive to ensure the code does not return.